After the FMV intro rolls, at the title screen, press UP, TRIANGLE, DOWN, X, LEFT, L1, RIGHT, R1. You should hear a tone and see new animation. The title screen will now read "Dragonball Z: Ultimate Battle 27", and you'll have five new characters to pick from.
Extra characters
To unlock 5 additional characters, press UP, Triangle, DOWN, X, LEFT, L1, RIGHT, R1 at the title screen. If entered correctly, the title should read: "Dragon Ball Z: Ultimate Battle 27"!
Gogeta: Special
Press Down, Right, Forward and Gogeta will shoot three large fireballs. A lot of energy will be required.
Gogeta: Dash Special Moves
When playing as Gogeta you can do two special moves while dashing (holding R1 or L1). While holding R1 or L1, press Square or X and Gogeta will fade out, reappear, and attack.
Rapid Fire
Press Half Circle Back, Forward, Circle.
Super Ghost Kamikaze Attack
Press Half Circle Back, Half Circle Forward, Circle. You can control it for as long as you want, but it takes a lot of energy.
Super Saiyan 3
Half Circle Back, Half Circle Forward, Square.
Vegeta: Fire Ball
Press Up, Down, Circle to summon a fire ball in front of Vegeta. Do this in the air directly above your enemy and it will still connect and hurt your opponent.
5 extra fighters
After the little movie where you see the 22 fighter's press up triangle down x left L1 right R1, and you will see another little movie featuring 5 extra fighter's.
