Finish the Novice Tournament and buy Adept Mode from Mr. Popo's Shop (in Edit Skills).

Advanced Tournament Level

Finish the Adept Tournament and buy Advanced Mode from Mr. Popo's Shop (in Edit Skills).

Unlock Yamcha

Beat a Cold-Blooded Assassin.

Unlock Trunks

Beat Perfect Form Cell Complete.

Unlock Hercule

Beat the Adept Mode of World Tournament.

Unlock The Great Saiyaman

Beat the Advanced Mode of World Tournament.

Unlock Additional Characters

Defeat each character in Story Mode.