I just wanted to again clarify to everyone that these are rookie teenage superheroes, so they shouldn't be too OP right off the bat. The one exception to this is the Hulk, as that kind of goes with all his incarnations. He has this huge monster raging inside him and can wreak havoc on both friends and enemies and cause a lot of collateral damage if he loses control. Because of that, he will be severely conservative in using his powers and only willingly unleash the beast when they are outnumbered and there is no other choice. 

Also, to make sure there is plenty of action for everyone, in most fight scenes I am going to include large waves of generic enemies that everyone can go against. That way each player can detail out their characters fighting a handful of baddies and no one is stepping on anyone's toes.