Depends on the transformation.

No transformation. I was just looking at motifs and resemblances. EG: I thought Yang might be Ursa-esque due to her strength. Though now that you mention it, I think the "kemono" fandom might like to see Ruby as a wolf Faunus.

And what about Weiss and Blake?

I'm drawing a blank. And I'm still on the fence about Yang. That's why I created this discussion.

I see...

Carry on.

Weiss can probably be most closely associated with the Queen Lancer. It's one of her most memorable fights and common summons, it can fire projectiles in hails like she does, and its stinger parallels how Weiss attacks with her rapier. This admittedly doesn't have anything to do with the Snow White inspiration but Weiss has always leaned into her fairy tale the least out of the four anyway.

As for Blake, I have no clue. You could go with the Sabyrs that appear in Volume 7, which are based off sabertooth tigers. Essentially the only connection you can make there with Blake is that they're both cats. Blake's fairy tale inspiration is Beauty and the Beast, but the Beast is a chimera of different animals and doesn't line up with any Grimm we've seen so far.

But Ruby is obviously a Beowolf, and Yang is obviously an Ursa, you can ascertain that just from their fairy tales alone, the wolf from Little Red Riding Hood and the bears from Goldilocks and the Three Bears.