Only 1 game mode? For multiplayer, you have timed /stock (lives) / first to so many kills battles, and you can play FFA or team battles. And for teams, you can play everyone against each other, 2v2, 1v3, or 2v1v1. So no, there is more than 1 game mode.If you mean only 1 way to kill people which is through supers, that is true though they wanted to try do something different rather than completing copy Smash Brothers.
See the rest here: PlayStation All-Stars PS Vita Review [PlayStationer.net]