Debug mode
Pause game play, then hold L2 or R2 and press Left, 
Up(2), Triangle, Right, Square, Left, Triangle, Up, 
Down, Right(2). 

Invincibility
Pause game play, then hold L2 or R2 and press Right(2), 
Left, Triangle, X, Up, Circle, Left. 

Unlimited Spirit Spells when acquired
Pause the game, then hold L2 or R2 and press Left, Triangle, 
Left(2), Circle, Left, Triangle, Right, Circle, Up(2), Down.