Man this is good...
It's only made better by it being the Rumble Arena "sprites"
Obviously you have to finish the Evolution version for that are you going to have WarGreymon do a hyper move, or have him be playable for a set amount of time...
Also for cosmetics...you could try to make the Digivolution more flashy, kinda like in the actual game, but that isn't that important...
But of course, this is 49% done, and I am probably saying things that may actually be done...
Other than that everything seems fine so far, good job