Make Rau Invincible:
Go to the title screen and press Circle, X, Square, Circle, X, Square, Circle, Square, X, Circle, X, Square, Circle, X . Then go visit the Sage. The Sixth card should be unlocked making Rau unstopple.

Tougher Opponents:
Go to the title screen and press X, Circle, Square, Square, X, Square, Circle, Circle, X, Circle, Circle, X

Easier opponents:
Go to the title screen and press X, Circle, Circle, Square, X, Square, Square, Circle

Disable Arena AI:
Go to the title screen and press X, Circle, Circle, Circle, X, Square, Square, Square, X, Circle, Square, X

Max Arrows:
Go to the title screen and press X, Circle, Square, Square, X, Square, Circle, Circle, X, Square, Square, X

Get Arenas:
Finish all challenges in a level to unlock a arena for that level

Use Any Weapon on Any Level:
Find each Tuku on ALL the levels to get a option at the Sage that allows weapons to be used on any level

Get Art and Outfits:
Finish the Body Count & time Attack in each arena to unlock these