As per our app rules, the only AUs we accept are canon AUs, with CRAUs being canon/canon AU versions with memories kept from other games, as well as (with certain limits during the app process) powers/traits from other games potentially carried over. If you want to keep the best of both worlds, we recommend apping their canon selves, but with CRAU included to outline what their AU life was like, and any AU-related abilities in the relevant section of the app. A character could be from canon but remember their AU life, and thus could be a mixture of the two.

If you want a more specific answer, feel free to let us know what exactly you have in mind, and we might be able to answer you better. We hope this helps!