Will you consider themainframe? Right now, our KH cast consists only of Sora, Riku Replica, and Terra, and I for one would love to see both of those characters! The game also meets all of your reqs except no powerloss, although there are occasions where powers may return, particularly during events. It's happened before.

I don't know how you feel about Digimon, and if it's not your thing, that's totally understandable. :) Just thought I'd extend the offer.