"Bonus Fighters
At the title screen, press Right, Left, Down, Up, Right, Left, Down, Up. You should hear a sound to confirm the code. Now start the game and you should have six more fighters.
submitted by Michael Medlin and SmurphyYEA"
"Unlock all characters except the final boss (Japanese Version)
At the title screen press: Right, Left, Down, Up, Right, Left, Down, Up. If done correctly you will hear a sound. Then press triagle 9 times and X 11 times after that you will hear the same sound.
submitted by boo"