Easy Battles:
To kill all enemies instantly press during battle while in character menu:
Start, Right, Left, Up, Down, R1, Square, R2, Square, Start, Down, Left, X.
Now exit the character menu and you are done.

Items:
To get 9 pieces of every item press while walking in game mode: Up, Right, L2, L2, Down, R2, R2, Up,
Down, R2, L2, Right, Left, Square, Square, Square.
You now hear a sound as confirmation.