Each character has a different Super Move that is unique to them in Injustice: Gods Among Us for the PS3, WiiU, and Xbox 360. Unlike Mortal Kombat or Street Fighter though, all Super Moves are performed the same way, by pressing the Flip Stance and Meter Burn buttons at the same time.
On Xbox 360: LT + RT
On PS3: L2 + R2
On WiiU: ZL + ZR
Here is the complete description of all of the Super Moves for all of the different characters in the game. Did you miss the window to get the exclusive pre-order bonuses? No worries, you can find Injustice: Gods Among Us DLC codes on Ebay.