Not much to say, just defeat a boss as Ms. Chalice

Defeat a boss with one of Porkrind's new weapons

I you didnt get this achievement while completing the game I recommend using the weapon "Crackshot" for this since this weapon has good damage and auto aim.

Defeat all of the King of Games' Champions

For me it didnt take a lot of time. I think the hardest one was the horse

Defeat every DLC boss except Chef Saltbaker

Defeat every DLC boss including Chef Saltbaker

Defeat a boss with one of Ms. Chalice's Super Arts

I wouldnt recommend using the second Super since it does not deal damage

Defeat a boss on Inkwell Isle IV without killing any of its minions

Esther Winchester is the best choice for this one since theres only 1 minion and its at phase 1

Have 9 HP at one time
The only way to do this is by equipping the Heart Ring and going to the Casino.

Strategy
First you must equip the 2 extra HP charm. After that you need to activate the Djimmi HP cheat. Just walk in circles on the map and Djimmi will double your HP. After that just go into a boss fight and you should have 9HP

Strategy 2
The first strategy is faster and more simple but if you want it to be a bit more challenging then feel free to do this one.
I recommend resetting until the first 1 UP is on the first boss.
Kill one of the alcohol boss and let the other 2 live. Dont kill them yet. What you wanna do is perry the eyeball attacks until you gain 3 HP UPs. After that finish off the boss and get the other 2 HP ups by using the Dice

Obtain an A-Rank or Higher on all DLC boss

Get an S rank on a DLC boss

I recommend going for Moonshine Mob for this one

Beat the King's Gauntlet challenge

You can select the King's Gauntlet after you beat all the other bosses.
In this challenge you must complete all the other challenges without dying. If you die at any boss you have to start over the whole thing! Your HP refills at the start of every new boss tho

Defeat 10 bosses with Ms. Chalice

Defeat the Secret Boss

This one is a little complicated. First you need to buy the Broken Relic. A Ghost should appear at the Graveyard if you have the Relic. At the graveyard you should be able to interact with all of the tombstones except for the middle one. The Contestants next to the shop will give you the answer. They say different things for everyone but they will mention some directions. For example the first contestant said to me: "As a winner, I never gave up! Left 'em looking foolish!" This means I have to go up from the middle tombstone and then left. You must press the first contestants tombstone first, then the second and the third or else it wont work. You also have to always start from the middle tombstone! If you did everything right you can now fight the Secret Boss

Defeat 8 bosses on regular difficulty with the Cursed Relic equipped

You will get the Cursed Relic after you beat the Secret Boss. The Cursed Relic will make the game even more harder. You start every fight with 1 HP, weapons are random and frequently change mid fight and Parries dont charge EX meter. You do get 1 HP if you hit 3 parries tho

Not an achievement but if you defeat all bosses (including King Dice and the Devil) with Ms. Chalice and after that talk to the Cactus girl in the DLC island you will get a Golden Skin for Ms. Chalice. You can equip it in the settings