Changed Characters Mid-Round
Normally, before beginning a round, you will choose one character to play as for the duration of the round, and normally cannot switch. However, you can with this cheat. Pause the game, then hold A+B on Controller 2. Now press Select on Controller 1 to cycle through the three main characters. Deselect and select the main character whilst paused to apply these changes.
Hard Mode
At the title screen, on controller two hold A and B and on controller one hold Select and B, then press Start two times.
Sound test
At the title screen, press and hold A, B and Select then press Start. If done right, the sound-test should appear.
Changed Characters Mid-Round...