Cheat Codes
In order to type your name in Japanese, access the main menu, then highlight the "New game" option and press the "X" and "A" buttons at the same time. You can also access a sound test by holding the "L" and "R" buttons down on the second controller when the Nintendo logo appears when you first turn on the system.
Unlockables
The only major unlockable feature in Super Punch-Out is the special circuit. You need to finish the minor, major and world circuits without losing (a combined 12-0 record).
Secrets
An expanded ending can be viewed if you beat the special circuit without losing a single fight. When you have knocked your opponent to the mat, you can regain some health by rapidly tapping all the buttons. If you hold "up" on the directional pad before the bell rings, your opponent's hands will be ready to block jabs; if you hold no direction, their hands will be down in order to block body shots.