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.