Invincibility & Level Warp:
While playing, press and hold Left trigger + Right trigger + Y + A + B + X. Then, while still holding them, press Start. After a level warp, press B to return to game.
Level 10, 45 skill points & 500,000 gold:
While playing, press and hold Left trigger + Right trigger + Y + A + B + X. Then, while still holding them, press White.