Take Beximus' Capcom Universe: Nexus of Heroes as a example. All characters using the same hyper combo background, same hit sounds, same super jump codes, etctera.
Try adapting all characters into the same system, like. Try to avoid reusing MvC1 intro, instead try to think on a intro 'inspired' by MvC1. The intro video really delivers that feeling since there's clashing effects, different versions of characters and especially different styles of gameplay with does not blender well with each other.
I think the biggest issue is the fact that game looks more like a compilation than a fullgame.If you're really going to make a fullgame, like, REALLY going to build a fullgame then there's some initial suggestions:
