Instructions
Hold down the R1 and R2 buttons and press Square, Triangle, Square, Triangle on your game controller.
Release the R1 and R2 buttons. Then, hold down the L1 and L2 buttons and press Right, Up, Right, Up on the game controller's directional pad.
Release the L1 and L2 buttons. Then, press the L3 and R3 buttons (analog thumb sticks) simultaneously. You should hear a chime indicating the code has been entered correctly.
Select "VS. Duel" mode from the main menu screen. Then, highlight Sasuke and press and hold the select button to unlock Sasuke's alternate form, Curse Mark Sasuke.