There's a couple of things and one I can accept because it's a flaw in MUGEN and I'd rather have the stage be full screen than otherwise. That one thing is that the HitSparks won't scale, so they're very big.
The one thing you can fix is this....
Having leftbound/rightbound shorter than 1000 will cause projectiles to explode before they go off screen and also when your opponent is in the corner the projectiles won't hit him.
Simply change your code to this....
leftbound = -1000
rightbound = 1000
topbound = 0
botbound = 0
and to make sure the players stop before the edge of the screen, change to this...
screenleft = 48
screenright = 48