Zen Nihon Pro Wrestling: Fight da Pon!

Debug Mode
Activate Pro Action Replay code, then hold X and press Select at any point other than the opening logos. (For best results, do this during an actual match, otherwise you're almost guaranteed to encounter some graphical issues.)

From here, select any item with A. You can get back to the main debug menu by pressing X + Select, and is the only way out of the unused menu items marked with "". The exceptions are the first one (which displays two hexadecimal numbers that can be changed with both controllers but have an unknown purpose) and the one underneath "EVENT" (which leads to a "siin" {scene} select that no longer seems to work correctly).

Sound Test
Selecting "SoundTes" from the above menu leads to the sound test screen, which displays each song's title one at a time. Again, X + Select goes back to the debug menu.