Level select:
At the main menu or during play, press L1, L2, , , L1, L2, , .

Invincible Hiro:
Pause the game and press L1, L2, , , L1, L2, , .

One-hit kills for Hiro:
Pause the game and press L1, L2, Up, Down, Left, Right, , , , Circle.

All magic:
Pause the game and press R1, R2, L1, L2, , , , .

All weapons:
Pause the game and press R1, L1, R2, L2, , , , .

Weapons stay strong:
Pause the game and press R1, L1, , , R2, L2, , .

Thanks to Revolution readers Scott Hutchinson and Marty McBean!