Game play is tag team, this means you gotta be able to be somewhat good playing with at least 2 characters to have a chance at victory. Combos are great on this game and somewhat easy to do, and there is even infinite combos for every single character on the game. The complete moves list for every character can be viewed here.
After defeating every team playing the CPU, you then fight Apocalypse, one of my favorite bad guy from Marvel Universe, but here he is really simple to defeat him. Then, you need to choose one of your character from your team as only one can be the winner. and that is the end of the game.