There are 25 almost perfectly balanced characters in all, with most of them extremely inventive and unique, save for the one that should be the most unique, inventive and balanced.
The other number that matters in most fighting game is the number of stages. But here, it really doesn't. There are quite a few, yet they are all the same. There are no breakable items, no levels, no nothing. You fight. Always on a 2D plane with no obstructions. Its a metaphor for the entire game, really. Its you, another (hopefully human) player attempting to be better than the other in one fight.