Anarchy In The Nippon 2 (PSX)

Alternate costumes and more options:
Beat single player mode under normal or higher difficulty setting. Press Down at the character selection screen to choose a new costume. And you can change the number of continues and rounds under options.

Slow motion replay:
Hold Circle before the replay begins.

Play as Boss:
Beat the game using all ten characters. Press Left at the leftmost or Right at the rightmost fighter at the character selection screen