To get Chi-chi and Sally beat the game with Capoera on any mode. You can use continues as much as you like.
Unlock Columbo (Japanese version)
To get Columbo beat the game with Shorty
Unlock Hustle Kong, Michael Doi, and McLoad (Japanese version)
To get Hustle kong, Michael Doi, and McLoad beat the game with all of the 10 starting characters (They will gradually appear on your character select)
OR
Hustle Kong - Beat the game in normal as Columbo or Kelly
Michael Doi - Beat the game in normal as Hiro or Sushi Boy
McLoad - Beat the game in normal as Comet or Columbo
Unlock Pander (Japanese Version)
To get Pander, beat the game with Robo-z in mix mode OR beat the game on normal with Robo-Z Gold
Unlock Robo-Z Gold(Japanese version)
To get Robo-Z Gold beat the game with Tsutomu, Kelly or Kitty-N
Unlock Sushi Boy
Beat the game in normal as Bi-O or Hiro.
Bonus level
Obtain a ranking of "Fever Time" in each level to unlock the Pander bonus level.
Alternate costumes
While a character is loading, hold Select to change their outfit.
Acid Line song
Enter the sound options screen and select music test. Hold Left or Right to quickly cycle through the song selections. Robo-Z Gold's song "Acid Line" will flash among the titles. Try stopping the cycling on that song to hear it.
More points
To earn a higher score, anticipate your player's first move and press the button before it appears on the screen (in the blank bar). The game will skip the first move and you will earn higher points.
Steal a solo
Attack an opponent just before their solo to steal it and do your own as well for extra points.
Shrink your opponents
Capoeira and ChiChi & Sally can shrink their opponent by attacking them. If you attack twice in a row, they will remain small for the entire battle.
Counterparts
Most players have counterparts, and they are:
Shorty - Columbo
Hiro - Hustle Kong
Kitty-N - Michael Doi
Comet - Sushi Boy
Kelly - McLoad
Capoeira - ChiChi & Sally