Play as SS Gotenks:
Beat the game on hard 9 times with Regular TRUNKS. Without dying and then after you've done that,go to Trunks and push the SELECT button 9 times

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.

Play as Goku 4:
At the title screen (with Goku on the right and the instructions for entering the sound test mode) press Right, Left, Down, Up, Right, Left, Down, Up. You should hear a tone. Next, press Triangle FIVE times, then press X 9 times. If done correctly another tone will sound and the menu screen will now have a cool picture of Super Saiyajin Level 4 Goku.

Self-Destruct:
While playing as Vegeta or Majin Boo, press forward, back, down, up and the fireball button (default is triangle) to perform a self-destruct. This does massive damage to your opponent if it connects and takes away about half of your Ki power.

Wire Frame:
For wireframe characters, hold SELECT while choosing a fighter

Alternate costumes:
Select two player or training mode. Then, press Square + X + Circle when choosing a character.

Sound test:
Press L1, L2, R1, R2, Start at the title screen. Press Select after choosing a song to view the lyrics and additional song information.

Super Baby:
Go to the character selection screen then hold Select and press Square while highlighting any character. Hold both buttons until the match begins.

Super attack:
Press the D-pad a quarter-circle backward and forward, then press Triangle.

Meteor:
Hold Forward and press R2. Your character should perform a kick. When you kick your opponent, press Triangle + Square, Triangle + X, or Triangle + Circle repeatedly.

Counter demo attack:
As soon as your opponent starts a demo, repeatedly press Square + Triangle + Circle. If done correctly (not too fast or slow), you should counter.

Super attack vs. super attack:
When your opponent starts doing a super attack, such as Kamehameha, Masenko, Final Flash, Big Bang Attack, etc., quickly press Triangle + Square + Circle repeatedly as your enemy starts the attack. As soon as your opponent unleashes his super attack, your character will use his own super attack. Keep pressing A + B while super attacking.