At the character selection screen, highlight the "?" icon. Then, press Select(7) followed by any button. Now Marionet will transform into the form of the opponent in each match.
At the character selection screen, highlight the "?" icon. Then, press Select(5) followed by any button. Now Shadow will transform into the previous opponent in the next match.
Beat the game with Gallon. Then highlight Gallon on the character selection screen and press Select + PP or Select + KK.
Beat the game with Bishamon. Then highlight Bishamon on the character selection screen and press Select + PP or Select + KK.
Begin a game in single player mode and do not lose in any round and defeat at least two characters with EX moves.
At the character selection screen, hold Select to choose Phobos.
Enable "Shortcut" mode. Then, highlight the desired hidden character location in shortcut character selection menu. Press Select to turn that character's name red and use that character.