To unlock alternate costumes, beat the game and then start a game on New Game+ mode on Hard difficulty. Then, use the key found in the Sunny treasure chest to open the lockers. Enter the girl's room to change your character's costumes.
Unlock the following characters for play in Versus mode by performing the corresponding tasks:
CHARACTER - HOW TO UNLOCK Aokiji - Defeat Aokiji on the Normal difficulty. Arlong - Defeat Arlong in Survival mode. Calgara - Defeat him in Round 20 of Survival mode. Enel - Defeat Enel on the Normal difficulty. Evil Guardian - Defeat Evil Guardian in Survival mode. Krieg - Defeat Krieg on the Normal difficulty. Kuma - Defeat Kuma on the Hard difficulty. Kuro - Defeat Kuro on the Normal difficulty. Monster Point Chopper - Defeat Monster Point Chopper in Survival mode. Moria - Defeat Moria on the Normal difficulty. Nightmare Luffy - Defeat Nightmare Luffy in Survival mode. Spandam - Defeat Spandam on the Normal difficulty. Wapul - Defeat Wapul on the Normal difficulty. Final Boss - Defeat the final Boss on the Hard difficulty.