The original opening sequence for the game features a nude Kasumi. First set your age to anything above 21 in the game options. You have to then get a top score in survival mode and use REALDEMO as your name in the rankings. Save your game, restart, and view the unlocked demo!
To see your characters in full 3D and preview their costumes, enter the vs. mode options and disable the "Quick Selector" function.
You can control the view point of the camera when your character is doing his victory pose. Just hold X and press the D-pad or Analog-stick to move the camera. Use B to zoom in and use the D-pad or Analog-stick to move the camera some more
You can see Kasumi in a special costume colour. You can't play with this costume, but you can force the computer to use it by playing the game using Kasumi's third (pink) costume in story mode. When you come up against the CPU Kasumi, you will see him appear in a black costume instead of the default pink!
Pause the game and press R, or Y + B, or X + Y.
Use the following combos to taunt your opponent:
Left, Right, Left, R
Right, Left, Right, R
Down 2 times, R
Back 2 times, R
(You can also substitute A + X + Y in place of R in the taunts.)
(When Zack does his taunt in his third costume, the dangly thing on his head lights up! hehe)
You can access images of the girls from the game in bikinis in the "Bonus" directory if you use the disc in a PC CD-ROM.
To get the cool Firefly level, select Arial Garden in Vs. mode using the right trigger or using Y.
In the options menu, under "other", the age you enter determines how bouncy the girls are - the higher your age, the bouncier they get :P. ie: if you say you're 99 you get ultra bouncy.
To view this hidden cut-scene, play as Ayane in story mode, and when you get to the battle against Kasumi you must K.O. her in the ice cave so that she lands approximately 10ft away from you. This will give you play the fireball FMV from the intro movie. You might have to try this several times to get it working right.
Hold down B and Y buttons, and Up-Right on the Analog control stick during a replay. The camera should spin around the fighters who are stuck in mid-combat a la Matrix style. Cool!