I love turn-based RPGs and I had this idea, I'm not sure if it would be fun in practice though.
The concept is that you are a normal guy vs supervillains (and their thugs etc) and you can't do much on your own. So when it is your turn to act you are normally just defending yourself, whilst you wait for timers to complete on allied superheroes who then fly in to help you. So think Final Fantasy battle system, except instead of a party it's one guy and your party is a group of off screen superheroes that fly in to assist, meanwhile you have to protect yourself from the devastating attacks from the supervillains.
So the battle system will be equal to something like you as the player have to defend yourself as much possible, shell it up by using armor, items to block attacks, using items on the enemy to distract them etc whilst waiting for the timers on the superhero character avatars to complete, then you select the avatars and they fly in to help (they would be the actual damage dealing attacks).
Thought it could be a neat idea, not sure how much fun it will be... thoughts?