Remember to give it a thumbs up and favorite if it helped you, I need that stuff for self validation :)

Use them. That's it... this section's only purpose is the first -and last- friendly reminder that you have like 20 Save Slots to use as backup.

Also, do try to prioritize the missables over anything else, this will save you headaches having to reload any of the aforementioned backups :)

Actually open it... No, really
Turns out the Bestiary in the Pixel Remasters is not only an awesome compendium, but actually it basically works as a Pokedex too. It is actually so good that there is no reason for the wiki link[finalfantasy.fandom.com] to be here anymore lol

Do note I am talking about the bestiary that can be accessed from the main menu when opening the game and NOT the in-game bestiary.

Display Map
This is the one feature that makes research obsolete, long story short just chase ? marks if you are planning to complete the Bestiary.

• World Monsters: These will show up as a big ? mark, if you go to the location where the mark is you will find a missing entry.
  
• Dungeon Monsters: While a little less precise, it will still show how many entries are in the dungeon and a ? mark for those missing so you know if you have completed it or need to keep running around.

Sidenote: Yes, I figured this out right before completing the Bestiary in FFIV and did not take any screenshots of the ? marks, use your imagination.

• Piano: After you get a lap dance in the pub you will be able to play the piano.
  Not missable. This is needed for some Bard Songs later.

• Area: This is a one time area.
  
• Bestiary: Entries below.
  191 - Sucker
  192 - Octokraken

• Chest: Stand in the rock seen on the screenshot below and wait for a couple of seconds.
  Not missable, just annoying.

Warning: There seems to be a bug on this area causing issues regarding one achievement. Please read below on the workaround shared by @Wesk Alber.

Originally posted by Wesk Alber:

[...] The Ship Graveyard is in itself a missable. You must - after completing the area, go back in despite it being a story required zone.

I just beat the game, did not have Adventurous Wayfarer Achievement. Found this bug on Reddit, and lo and behold, after fighting one enemy inside I got the achievement. So while bugged, First World Ship Graveyard is a missable location. Re-enter to make it count.

• Piano: Play the piano in the pub, no lap dance this time tho' :c
  Not missable. This is needed for some Bard Songs later.

Originally posted by GamerWithAQuest:

It's worth noting for the completionists that Carwen will only have 3/4 items when leaving the first world.

• Bestiary: During the boss fight against Magissa you have to let her summon Forza.

• Item: Buy Iron Shield on the shop.
  
• Item: Buy Kenpo Gi on the shop.

• Item: Do not release the stupid Lone Wolf under any circumstances unless you enjoy loot being stolen.
  
• Summon: Defeat Shiva on the Water Tower behind the waterfall.
  Yes technically this is a separate area. No, I am not making another guide section for it.

• Area: This is a one time area, do not defeat the boss until you are ready to leave.
  
• Chest: All 4 chests.
  
• Blue Spell: Pond's Chorus can be learned from Elf Toad.
  You will need to kill all other enemies to leave only one left.
  
• Bestiary: Entries below.
  027 - Ricard Mage*
  028 - Wyvern
  029 - Pas de Seul
  * Ricard Mage gives you a second chance to find and kill once you reach Fork Tower. Get it here to avoid headaches.
  
• Extra: After defeating the boss there will be a crystal you can't get which will be acquired much later in the game.

• Piano: Play the piano in the pub.
  Not missable. This is needed for some Bard Songs later.

• Area: This is a one-time area, or at least it will be by the time you can get the chests and find monsters on it.
  This area becomes "active" after killing the boss on Fire-Powered Ship. You will have 10:00 minutes to plunder it, grind if you do not feel ready.
  There is a save spot right on the entrance of the area, you know what to do with it.
  
• Chest: There are 15 chests in this location, almost all of them are Monster-In-A-Box.
  
• Blue Spell: Learn Aera from Gigas.
  IMPORTANT: Aera is permanently missable after killing Azulmagia, so make sure to grab it now.
  
• Blue Spell: Learn Death Claw from Iron Claw.
  
• Bestiary: Entries below, get them before this location explodes.
  041 - Sergeant
  042 - Sorcerer
  043 - Cur Nakk
  044 - Gigas
  238 - Iron Claw: On the main entrance to the castle you will have a mandatory fight with 1 Sergeant and 3 Cur Nakks, kill all Cur Nakks first and then let Seargant transform. All other Seargants in the Castle will flee instead.
  Refer to the screenshot below if you are unsure of the fight location.

P.d. ♥♥♥♥ Square for that bestiary entry. And no, I am not butt hurt cause I had to do this stupid area twice.

• Summon: Follow the "secret" path on the Library and defeat Ifrit.
  Not missable.
  
• Blue Spell: Learn Magic Hammer from boss fight againstByblos.
  Not missable, can be learned later.

• Piano: Play the piano in the pub.
  Not missable. This is needed for some Bard Songs later.

• Piano: Located on the Bard's house in the Southeast.
  Not missable. This is needed for some Bard Songs later.

• Spell: Toad will be given to you after you do a circle around the flowers on the Northwest area.
  Not missable.
  
• Song: Romeo's Ballad can be obtained by answering "Yes" to the Bard.
  To get to where the Bard is you need to get your ass beat by the only sheep that doesn't move.
  
• Summon: Defeat Ramuh on the forest to the East of the village and use the spell from your inventory.
  Technically it can be found later as well. And yes, again I am cheating to remove a guide section.

• Song: Alluring Air can be learned from Bard on Bartz's house after interacting with the Music Box.

• Item: Javelin is stolen from Sand Bear.
  Not missable since Sand Bear shows up on later areas, but the weapon will be kinda useless by then lol

• Area: After fighting the boss this area will no longer be accesible.
  
• Chests: All 12 chests.
  
• Blue Spell: Learn White Wind from Enchanted Fan.
  You will need to use the Control ability from a Beastmaster.
  Not missable.
  
• Blue Spell: Learn 1000 Needles from Lamia.
  You will need to use the Control ability from a Beastmaster.
  Not missable.
  
• Blue Spell: Learn Level 4 Graviga from Ghidra.
  Ghidra is immune to !Control and will cast this spell on death.
  Your Blue Mage needs to have a level number divisible by 4.
  Not missable.
  
• Bestiary: Entries below.
  062 - Ra Mage
  064 - Stone Mask
  065 - Enchanted Fan
  066 - Lamia
  067 - Archeotoad
  068 - Hydra
  069 - Ghidra: This is a rare encounter that is easier to find in the room with the 2 chests that has a whole on it from where you can see the blue knight dude.

IMPORTANT:After completing this area Galuf will leave your party until you make the -permanent- travel to the second world. You have been warned if you want him to be there during your completion of this world.

After revisiting the 4 Meteors again and leaving through the portal on the middle of the world you will permanently move to another world, making a lot of things on the first world permanently missable, you may want to complete them before advancing forward.


Equip the job on at least one of the party members, raise it to level 2, equip the Learn ability, wait for the monster to cast the spell, make sure you get hit but don't die from it and then win the fight, not convoluted at all!
As a neat trick you can use a Beastmaster's Control ability to force the monsters into saving you time.

Also, should you miss any of these they can be learned from other monsters later on.

• Aqua Breath: Learn from Dhorme Chimera on Library of the Ancients.
  
  
• Level 5 Death: Learn from Page 64 on Library of the Ancients.
  You will need your Blue Mage character to be a level divisible by 5 for it to not Miss.
  
  
• Level 4 Graviga: Learn from Ghidra on Ronka Ruins.
  Ghidra is immune to !Control and will cast this spell on death.
  You will need your Blue Mage character to be a level divisible by 4 for it to not Miss.
  
  
• Pond's Chorus: Learn from Elf Toad on Tower of Walse.
  You will need to kill all other enemies to leave only one left.
  
  
• Flash: Learn from Headstone on North Mountain.
  You will need to use an ether on this enemy so it has enough MP to cast.
  
  
• Moon Flute: Learn from Page 256 on Library of the Ancients.
  
  
• Death Claw: Learn from Iron Claw on Karnak Castle.
  
  
• Aero: Learn from Moldwynd on Wind Shrine.
  
  
• Aera: Learn from Gigas on Karnak Castle.
  
  
• Flame Thrower: Learn from Prototype on the islands Southwest of Crescent.
  
  
• Goblin Punch: Learn from Black Goblin on Wind Shrine.
  
  
• Dark Spark: Learn from Black Flame on the islands Southwest of Crescent.
  
  
• Off-Guard: Learn from Page 256 on Library of the Ancients.
  
  
• Transfusion: Learn from Mythril Dragon on the forest outside Library of the Ancients.
  You will need to use the Control ability from a Beastmaster.
  
  
• Vampire: Learn from Steel Bat on Pirates’ Hideout.
  
  
• Magic Hammer: Learn from Byblos on Library of the Ancients.
  
  
• Self-Destruct: Learn from Motor Trap on Fire-Powered Ship.
  You will need to damage it with Thunder first.
  
  
• ???: Learn from Wild Nakk on the forests North of Karnak.
  
  
• 1000 Needles: Learn from Lamia on Ronka Ruins.
  You will need to use the Control ability from a Beastmaster.
  
  
• White Wind: Learn from Enchanted Fan on Ronka Ruins.
  You will need to use the Control ability from a Beastmaster.
  
  
• Missile: Learn from Motor Trap on Fire-Powered Ship.

You should have most if not all of these as the ones not mentioned on other segments of the guide are super easy to get, regardless just make sure you got em all:

• Chocobo: Buy on Walse for 300 gil.
  
  
• Sylph: Buy on Walse for 350 gil.
  
  
• Remora: Buy on Walse for 250 gil.
  
  
• Shiva: Defeat her on the cave behind the waterfall on Castle Walse.
  
  
• Ramuh: Defeat him on the forest East of Istory.
  
  
• Ifrit: Defeat him on Library of the Ancients.
  
  
• Titan: Defeat Titan on Karnak Meteorite right before moving to the second world.

These add up to a neat 100 entries.

• 01 to 69
  
• 191 to 196
  
• 229 to 253

Worth mentioning monsters are:

• 030 - Jackanapes: Found on Walse Castle B1.
  This fight always gets you from behind.
  
  
• 056 - Prototype: Found on two of the islands Southwest of Crescent.
  Lets kill three birds with one stone and use the ability Control from a Beastmaster to have him teach your Blue Mages the spell Missile and then commit suicide with Self-Destruct.
  Now find another one and let it cast Flame Thrower then Control it and have it Self-Destruct too.

Lastly, your map should look more or less like the one below. You can also use the in game item "World Map" to confirm if you have left stones unturned.
You should have all Chests and Items in all locations, except those stating otherwise.

• Wind Drake
  
• Airship
  
• Tule
  
• Carwen
  Items 3/4
  
• Castle Walse
  
• Walse
  
• Castle Tycoon
  
• Karnak
  
• Library of the Ancients
  
• Crescent
  
• Black Chocobo Forest
  
• Catapult
  
• Lix
  
• Istory
  
• Tycoon Meteorite
  
• Cave
  
• Pirates' Hideout
  
• Wind Shrine
  
• Ship Graveyard
  
• North Mountain
  
• Walse Meteorite
  
• Karnak Meteorite
  
• Fire-Powered Ship
  
• Desert of Shifting Sands
  
• Gohn Meteorite
  
• Jachol Cave
  
• Water Tower

After reaching Galuf's World and camping on the small forest you will be forced into a fight after which you will be taken to Exdeath's Castle.

• Bestiary: 254 - Abductor will be missed if Bartz is defeated.
  This is most likely no longer the case for the PR but nobody wants to lose to a lame Abductor to check amirite ;)
  Yet again another instance of me cheating my way into not making a guide section for a nameless forest you visit once.
  
• Item: Spear is stolen from Shell Bear.

• Bestiary: Before finishing this area make sure to get all entries below.
  076 - Merrow
  077 - Flying Killer
  078 - Little Chariot
  079 - Neo Garula

• Bestiary: Entries below, get them before leaving.
  089 - Acrophies
  090 - Moogle Eater
  091 - Lesser Lopros
  
  Note: None of these seem really missable -yet- since as far as I can tell you can enter the hole again... so... get them anyways just in case?

• Item: Steal Genji Gloves from Gilgamesh.
  
• Bestiary: As confirmed by @Zakumi Keizudo if you defeat Gilgamesh before he summons Enkidu you will lose this entry.

• Location: This is a one time area.
  
• Blue Spell: Learn Level 2 Old from Level Tricker.
  You will need to have your level be divisible by 2.
  You may also need to use Control ability from a Beastmaster.
  You will also need to use Mix ability from a Chemist, to reflect the spell since the monster will only cast it on itself, quoting our friend Tyrax:
  

  Originally posted by Tyrax Lightning:

  When Controlling the Level Tricker, it'll only cast L2 Old on itself & the other baddies... it's not possible to re-target it onto the Heroes for unknown reasons. Reflect is needed to bounce the L2 Old off of a Monster onto a Hero with Learning.

• Blue Spell: Learn Level 3 Flare from Red Dragon as a monster-in-a-box encounter.
  You will need to have your level be divisible by 3.
  You may also need to use Control ability from a Beastmaster.
  You will also need to use Mix ability from a Chemist, to reflect the spell since the monster will only cast it on itself.
  Note: Personally I prefer to learn it slightly later since you have to either keep your Blue for the whole area or know the exact chest. I do not know the exact chest since I added this spell here due to one of this guides' comments, so accept my apology and do let me know the exact chest location if you can :)
  Plus, turns out the dragon is not even guaranteed, so just move on and F this one for now.
  
• Blue Spell: Learn Time Slip from Traveler.
  
• Bestiary: Entries below, get them before fighting the boss.
  106 - Neon
  107 - Magnetite
  108 - Reflect Knight
  109 - Traveler
  110 - Level Tricker
  111 - Gravitator
  112 - Ziggurat Gigas

• Chests: Be diligent about all 12 chests on this area on your first visit, shortly after the second savespot the area will change, you should have gotten 9 chests prior to the change, 1 during the change before jumping on the hole (this sentence will make sense in context), and the last 2 after the change.
  
• Blue Spell: Learn Lilliputian Lyric from Mini Magician.
  
• Bestiary: Entry below should also be found before the area suffers changes.
  122 - Wyrm

Extra 1: Credits to @asmoranomar and @Wesk Alber for the above.

Extra 2: You may want to make a backup save before completing this area for no reason whatsoever.

IMPORTANT: Defeating Exdeath on Floor 13 will take you go to the next world without a way of coming back. Please make 100% sure you have everything listed in the section "Galuf's World - Completion" before even entering this area, just to be safe.

The entries below can be found in this dungeon, with the ones exclusive to it listed individually on this very same section.
030, 071, 072, 121, 123 to 134, 158, 255 and 271 to 273.

• Bestiary: Entries below, get them in the basement before lifting the illusion.
  071 - Tarantula
  072 - Shell Bear
  
• Bestiary: The entry below is not missable, just annoying to get.
  158 - Oiseaurare: On the room with the moving "bridge" make the bridge end on the second wall from the left, this one seems to consistently get the monster to spawn.
  
• Item: Power Staff is dropped by 128 - Black Warlock.
  
• Summon: Defeat Carbuncle, to reach him you need to position yourself on the north skull on the same floor where you see the summon light.
  
• Item: Steal Genji Helm from Gilgamesh after he transforms
  
• Item: Let Gilgamesh transform to his final form and use his crappy new sword, the fight will end automatically and you will get Excalipoor.

After finishing the events of Exdeath's Castle's second visit several things will once again become missable, I am sure you understand why.

As such you may want to do all this stuff before entering the Castle.


You know what to do by now.

• Level 3 Flare: Learn from Red Dragon on Castle Exdeath.
  You will need to have your level be divisible by 3.
  You may also need to use Control ability from a Beastmaster.
  You will also need to use Mix ability from a Chemist.
  
  
• Level 2 Old: Learn from Level Tricker on Barrier Tower.
  You will need to have your level be divisible by 2.
  You may also need to use Control ability from a Beastmaster as mentioned by @Wesk Alber.
  
  
• Lilliputian Lyric: Learn from Mini Magician on Forest of Moore.
  
  
• Time Slip: Learn from Traveler on Barrier Tower.
  
  
• Aeroga: Learn from Metamorph on Ghido's Cave.
  You will need for it to convert into Enchanted Fan first.

Only two on this world.

• Golem: You will encounter Golem randomly in Drakenvale, eventually the encounter will have 2 monsters bullying him (it?), kill them before they kill Golem and then use the item. You can repeat the encounter if you fail.
  
  
• Catoblepas: Defeat it and use the item.
  To find this annoying guy use the submarine to reach the cave on the Northwest of the map and then find it as a random encounter just outside the Chocobo Forest.

• Regole: The hidden hallway to reach the Piano is in the SouthWest corner of the pub.
  
  
• Moore: Play the piano in the pub.

• Requiem: Talk to one of the Wolves running around in circles on the Northeast section of Quelb.
  
  
• Swift Song: On the King's Chamber of Surgate Castle.

91 new monsters for an annoying uneven number total of 191.

• 70 to 137 except 87
  
• 139
  
• 176 - 177
  
• 254 - 273
  IMPORTANT: Some of these entries are in the final area of this world, which is also the point of no return, the specific entries are:
  030, 071, 082, 121, 123 to 134, 158, 255 and 271 to 273.
  You can see the screenshot in the specific section "Exdeath's Casle - 2nd Visit" of this guide too if you need visual reference.
  
  Note: If you are coming from a previous version of the game, entries 254 to 273 are renumbered from for this one, referencing the list below just for the fun of it.
  Abductor
  Gilgamesh
  Gilgamesh
  Tyrannosaur
  Abductor
  Golem
  Dragon Pod
  Dragon Flower
  Gilgamesh
  Enkidu
  Atomos
  ???
  ???
  ???
  ???
  Catoblepas
  Gil Turtle
  Carbuncle
  Gilgamesh
  Exdeath

Worth mentioning monsters are:

• 086 - Shield Dragon: Have Beastmaster use Control and force it to suicide by Blaze.
  
  
• 270 - Gil Turtle: Prepare Blizzaga, Float, Golem and then effing avoid this one like the plague anyway, you will have a bad time lol.
  
  Bonus strategies proposed by users.
  

  Originally posted by dschepler:

  Equip a knight with Bone Mail and Genji Gloves, and then have three bards (or other jobs with Sing equipped, of course) in critical HP. Beforehand, cast Float on the party (which also helps with the random encounters in the area). Then, start off by having knight use Guard, then the bards spam Requiem, and use auto-battle so the knight's Guard doesn't have gaps. That strategy worked well for me whereas with the others I always eventually failed to e.g. get Blink up again in time.

  
  

  Originally posted by Aethelia:

  A Time Mage, two White Mages, and a Black Mage. Time Mage for Float and Haste. White Mages for Healing and Esuna if needed, but mostly for Blink. Black Mage for Ice spells, to be used when everyone has Blink. You can have two Black Mages to speed it up if some or all of your characters have Image so they can get Blink back for free.

  
  Update: Some of the strats previously available for Gil Turtle on this section relied on a bug (most likely unknowingly) that has since been fixed, as such I still want to thank Cetae and Zakumi Keizudo for sharing and this is my way to keep them credited even after deleting the strats.

Lastly, your map should look more or less like the one below. You can also use the in game item "World Map" to confirm if you have left stones unturned.
You should have all Chests and Items in all locations, except those stating otherwise.

• Wind Drake
  
• Submarine
  
• Regole
  
• Moogle Village
  
• Castle of Bal
  
• Quelb
  
• Moore
  
• Surgate Castle
  Items 0/1
  
• Chocobo Forest
  
• Castle Exdeath
  
• Big Bridge
  
• Kuza, the Sealed Castle
  
• Moogle Forest
  
• Drakenvale
  
• Forest of Moore
  
• Cave
  
• Gil Cave
  
• Underground Waterway

Sidenote: Our friend @Craig wants you to remember that one item in Drakenvale that you said to yourself you would find later and had already forgotten, it is on a pile of bones, you will get the ! prompt on the correct one.

• Item: Approach the small house on the Southwest corner of the map from behind and you will be able to go past it into a hidden path on the forest, eventually you will find an NPC that will let you choose between two chests. Whichever you choose makes the other one missed.
  Brave Blade: Pretty good stat wise for now.
  Chicken Knife: It gets stronger the more you flee from battle.

• Song: Before completing the Pyramid you should go to the top floor of the Library of the Ancients and get Mana's Paean.
  
• Area: Beating the boss of the Pyramid will make the Library of the Ancients no longer accessible.
  
• Item: Power Staff is dropped by 128 - Black Warlock.
  Unlike the previous location this time the Black Warlock can only be found with a 50% chance of spawning on a monster-in-a-box chest. Told you you'd hate yourself.
  
• Blue Spell: Learn Doom from The Damned during a monster-in-a-box encounter.
  For those of us that are not fans of the monster-in-a-box learning, we will learn this spell in the next section of this guide at another area.
  Note: You may need to control it and give it an ether.

We will take a break from the missable content for a second to talk about what I consider to be an annoyingly unclear questline, yes even with the on-the-nose hints.

Just coming out of Pyramid of Moore you got a fancy new Tablet that you are meant to take to Kuza, the Sealed Castle to redeem your first 3 Sealed Weapons.

There are 12 weapons spread across 4 tablets on the following locations:

• Pyramid of Moore: Summons Bahamut to the world.
  
• Island Shrine: Allows you to enter Fork Tower for Holy and Flare.
  Note: Make sure to learn the Blue Mage spell Doom from The Damned if you hadn't learned it before.
  You will need to control it and give it an ether, poor bastard had been grinding exp and depleted it.
  
• Great Sea Trench: Grants the Meteor spell.
  
• Istory Falls: Summons Leviathan to the world.

• Location: This is a one time area.
  
• Chests: There are 4 chests, 2 on each side of the tower.
  The game cheats you as once you "split" the map also splits them but LIES to your face by showing 0/0 chests despite having a clear 0/4 before entering.
  
• Bestiary: Entries below, get them on the Magic Side (Left) before fighting the boss.
  027 - Ricard Mage*
  162 - Tiny Mage
  163 - Chrono Controller
  164 - Flamemancer
  * This is your last chance if you did not get entry 027 before.
  
• Bestiary: Entries below, get them on the Physical Side (Right) before fighting the boss.
  165 - Dueling Knight
  166 - Iron Muscles
  167 - Berserker

• Summon: Defeat Ramuh and use the spell from your inventory.
  Ramuh will only be here if not obtained in World 1.
  
• Item: Titan's Gloves can be stolen from boss Azulmagia.
  Steal chances are like 3% just so you know...
  
• Item: The final Elven Mantle available in the game can be dropped by the boss Halicarnassus.
  
• Item: Tinklebell is a rare drop only from boss Twintania when it is not charging up for Gigaflare.
  While charging Gigaflare you can steal a Titan's Axe (only two of this axe exist in the game). It can also drop a Murasama Katana but you can get this elsewhere. I would recommend getting the Tinklebell but you do you, or follow the strat below on this section to get both.
  
• Item: Steal Genji Shield from Gilgamesh on its own fight.
  
• Scene: Gilgamesh will show up when Necrophobe has less than 10,000 HP left.
  
• Item: Steal Genji Armor from Gilgamesh on Necrophobe's fight.

Originally posted by Epirasque:

Quoted text

• Here is my strategy for getting both the titan's axe as well as tinklebell from twintania, took me ~3 minutes per try with a ~6% chance of success (for the tinklebell) per try:
  
  
• All party members should know blue magic, at least one should know steal (not mug!), ideally one more knows time magic. maxhp from monks can help as well.
  
  
• Equip them all with a flame ring (aegis and/or elemental shields can work too).
  
  
• At the beginning of the fight, cast mighty guard to shell the party. if you have time magic, cast hastega as well.
  
  
• Then don't attack at all (it provokes counters) but instead focus on survival e.g. casting white wind once or twice.
  
  
• Once the screen flashes and the charge-up message appears, use death claw (has an extremely high success rate during charge up) and try to steal the titan's axe (if the steal works it will always be a titan's axe, its not a rare item).
  
  
• You have a narrow time window here, so if you have bad luck with the steals cast stop on twintania to prolong that window.
  
  
• Once the steal is done, wait until the gigaflare hits. afterwards feel free to heal your party a bit.
  
  
• Now either wait until twintania uses its next ordinary ability or until you notice a short pause in the ATB-chargeup - that is when it changes back into its less vulnerable form (with different item drops). you can verify this change by trying another steal, if it says it doesn't have an item to steal then it is still in the vulnerable form and you have to wait.
  
  
• Once you are certain it changed, simply hit it with an ordinary attack. due to the deathclaw earlier on it has less than 10 hp and dies easily.
  
  
• If it didn't drop the tinklebell then load your quicksave and try again.

Ok this place is convoluted enough to earn its own section even if nothing here is missable.

Head to the bottom of the map and find a small forest more or less in the Merged World equivalent of where Prototype was on Bartz's World. Roam around the forest and eventually a "random encounter" will take you to the village.
This whole place is easier to navigate if you have been to its Interdimensional Rift parallel.

• Item: Take the "hidden" door behind the pub, there is an item on the second barrel from the bottom to the top.
  
• NPC: Continue inside the pub from where you got the item above and then the stairs on the left side, you will see a man that wants you to go around the world on a yellow chocobo, this random request is an actual questline. More on this below.
  
• Item: Complete the NPCs request and come talk to him again to get your reward.
  
• Piano: Continue making your way from the NPC above until eventually you descend down some stairs after a pot that heals you fully, take a left through the hidden wall and again continue left through another hidden wall on the small room that has some stairs down.
  
• Chocobo: Following the path to the piano take the stairs between the two hidden walls right before the piano.

Strictly speaking you are not really going around the world, anyway go grab your Boko, mine was right outside Ghido's Cave, the idea is to "hug the walls" and more or less go around all these areas:

• Karnak
  
• Surgate Castle
  
• Quelb
  
• Castle of Bal
  
• Phantom Village
  
• Crescent
  
• Interdimensional Rift
  
• Tule
  
• Ghido's Cave

Screenshot below is more or less the route I did.


Of course this place has secret merchants, why wouldn't it?

• Armor Shop: Interact with the crate right to the left when you enter the shop, it will open a path to an NPC and the secret merchant.
  
• Weapon Shop: On the hallway where we took a left to find the Piano take a right instead and go through the stairs at the end of the hallway, there you will see the secret merchant.
  
• Magic Shop: Take a left outside of the shop and enter through the hidden door to find the secret merchant.

This is it, time to go around and finish everything.

• Job: Mime can be found underwater on Tower of Walse by reaching the bottom and "fighting" a boss. And by fighting I mean standing still until he acknowledges this as a valid form of mimicry.
  Do keep in mind you have a time limit in this area so plan ahead for boss dialogue.
  
  Note: There used to be a glitch where you would not get the bestiary entry unless you beat the ♥♥♥♥ out of this monster, user @FenecK confirms this has been fixed, keeping the mention of this having been a thing for the sake of documentation.
  
  
• Item: Magic Lamp can be obtained on Istory Falls by arriving on Boko.

You know what to do by now.

• Roulette: Learn from Death Dealer on Interdimensional Rift - Ruins.
  
  
• Mind Blast: Learn from Twintania or Mindflayer on Interdimensional Rift - Inner Sanctum.
  
  
• Mighty Guard: Learn from Stingray on a sea battle just outside of Carwen.
  You will need to use the Control ability from a Beastmaster.

• Syldra: Revisit the Pirates Hideout to reconnect with an old friend.
  
  
• Odin: Go to Jachol Cave and make it all the way to the end, interact with the wall to climb and reach Castle of Bal - B2, after a looong hallway you will find Odin, he will give you 1 minute to defeat him.
  
  
• Phoenix: Use the Black Chocobo of Phantom Village to land on the small forest in the Northeast desert of the map, from there walk your way Southwest to arrive at Phoenix Tower.
  This Tower has 30 floors and each floor has a door protected by a boss and a normal door, you will want to "fail" some doors for bestiary completion anyway so have fun...
  On floor 30 refuse to harm the dragon.
  Sidenote: Bring tons of Elixirs and give them to the Magic Pots, again for Bestiary and for Item completion.
  
  
• Leviathan: Found on Istory Falls by submarine after getting the tablet.
  
  
• Bahamut: Use the Black Chocobo of Phantom Village to land on the small forest in the Northeast desert of the map, from there walk your way to North Mountain and prepare to fight.

After having played most (if not all) Pianos you need to travel to Crescent and enter the Bard's house at the bottom right corner of the map, play the piano for him for your rewards.

• Sinewy Etude: Play 7 Pianos.
  
  
• Hero's Rime: Play 8 Pianos.

You should have them all now. Worth mentioning monsters are:

• Magic Pot: Found in Phoenix Tower, can only be defeated by giving it an elixir.
  
  
• Mover: Found in Interdimensional Rift - Inner Sanctum, the best way to level up your jobs.
  
  
• Omega: Found in Interdimensional Rift - Cave.
  Equip Flame Ring, !Rapid Fire and !Spellblade Lv. 6 to make your Rapid Fire powered by Thundaga, now play a game of who melts who first.
  
  
• Shinryu: Found in Interdimensional Rift - Inner Sanctum inside a chest.
  Equip Ice Shield, Coral Ring and melt him with Zeninage IDGAF lol.

Does this monster look like Aerith to anyone else lol?

Use the World Map item if you are unsure, your maps should look like the screenshots below.

Surface:

• Black Chocobo
  
• Chocobo
  
• Airship
  
• Tule
  
• Karnak
  
• Surgate Castle
  
• Carwen
  
• Crescent
  
• Catapult
  
• Jachole
  
• Regole
  
• Castle of Bal
  
• Quelb
  
• Moore
  
• Phantom Village
  
• Cave
  
• Pirates' Hideout
  
• Ghido's Cave
  
• Guardian Tree
  
• Pyramid of Moore
  
• Istory Falls
  
• Wind Shrine
  
• North Mountain
  
• Jachol Cave
  
• Fire-Powered Ship
  
• Island Shrine
  
• Kuza, the Sealed Castle
  
• Drakenvale
  
• Phoenix Tower
  
• Interdimensional Rift
  
• Istory Falls
  
• Cave
  
• The Rift

Underwater:

• Submarine
  
• Cave
  
• Great Sea Trench
  
• Kingdom of the Dwarves
  
• Tower of Walse
  
• ???

Hope this guide helped, now go play FFVI.