Black Ball Assault mini-game:
Enter AZY as a code at the cheat screen. Then, highlight "End" and press A or C. Black Ball Assault is a Pong-like mini-game.
Cheat mode:
Note: This code requires a six-button controller. Hold A + Y + Z at the title screen to display the cheat screen.
Invincibility:
Enter MTK as a code at the cheat screen. Then, highlight "End" and press A or C.