Hold I + II at the title screen. With those buttons held, press Run to select players and press Run again to select type of game. The following numbers will be displayed that will enabled the corresponding feature in the game.

1: U.S. flag over player one.
2: Light bulb over player two or CPU.
3: Unknown
4: Tournament mode ending.
5: No game music.
6: No crowd noise.
7: On-screen scoreboard.
8: Unknown