Each of your Super Heroes has Special Powers that define them as a Marvel Super Hero. Some are offensive, some are boosts for you team, and some are powerful enough to change the tide of the most difficult boss battle.
To use your Special Powers in battle, press RT/RB to bring up the menu. There are four icons, each mapped to the A/X, B/O, X/Square or Y/Triangle button. Press the appropiate button to use the power.
You have to have enough Energy/Stamina to use the Power.
Xtreme attacks are the most powerful move your hero will have. Instead of using Power to execute, you need momentum. You must have full (100/100) momentum to use an Extreme attack. Enemies can also drop tokens that will instantly fill the collector's momentum bar, or one of his allies if the player already has a full bar.