When selecting a character in either versus mode or battle mode, hold L1 + R1.
Play as Rogue
Select versus mode. Then on the character select screen, press the following buttons. For player one, highlight Ranma and press Right(3), Down, Left(3) Up, and any button to select Ranma. For player two, highlight Ranma's friend and press Left(3), Up, Right(3), Down, and any button.
Sound test
Set the CPU level to "1", time limit to "30", and rounds won to "1". Then, select story mode and uncover all stones except one. Now save and reload the game at regular intervals to avoid mistakes. A special red stone will appear to the right of the starting location after only one stone remains. Uncover the red stone to enter sound test mode.