Get All Costumes:
Go to the main menu and press Triangle, Circle, Triangle, Square, Square, Square, L1 + L2.

Pick level:
Go to the main menu and press Triangle, Circle, Triangle, Square, Triangle, Circle, L1 + R1.

Unlock Cerebro Files:
Go to the main menu and press Triangle, Circle, Triangle, Square, Square, Square, R1 + R2.

Unlock Debug menu:
Go to the main menu and press Triangle, Triangle, Circle, Circle, Square, Square, Circle, Circle, L1+ R1 + L2 + R2. The debug menu will be available after you pause the game