Who else besides Ichigo has a transformation bankai?

Question

I know that in the Seireitei there are many different kinds of bankais and was wondering if Ichigo is the only one that full on transforms when he activates his bankai.

Answer 1

I found Sode no Shirayuki (袖白雪) / Hakka no Togame (白霞罸) to be worthy of being called a full-transformation Bankai.

Depending on argumentation, you could also classify the newly revealed Bankai of Zaraki Kenpachi as a full-transformation Bankai. Even though the specifics are unclear as of now, the artwork suggests it has a similar mechanism like Ichigo's and Rukia's Bankais.

Additionally, there are a few that partly transform the user, as mentioned in Dimitri's answer.

Answer 2

Yes, so far Ichigo is the only one that has a full-transform Bankai. With the list of currently known achieved Bankai we can conclude that there are no other Bankai that include a full transformation.

We do know there are some that partially transform such as Daiguren Hyōrinmaru, which causes wings and a tail to sprout. And so there are a few more Bankai that either overlap quite a piece of body or add parts such as with Daiguren Hyōrinmaru.

There is yet another known full body transformation. But it is not directly a Bankai, and it would be the Resurrección.