Aokiji
Clear event battle with Luffy, Zoro, Nami, Usopp, Sanji, Chopper, Robin, Buggy, Kuro, Krieg, Arlong, Smoker, Bon Clay, Crocodile, and Foxy. Then, play event battle again with Luffy. In the final stage you will battle Aokiji. To unlock Aokiji you must use your level 2 special.
Arlong
Clear event battle with Nami.
Bon Clay
Clear event battle with Chopper.
Buggy
Clear event battle with Zoro.
Crocodile
Clear event battle with Robin.
Don Crick
Clear event battle with Sanji under the normal difficulty setting.
Enel
After clearing event battle with Luffy, Zoro, Nami, Usopp, Sanji, Chopper, and Robin, complete their move list in training mode. A picture should flash by of Enel challenging you. Then, play a regular tournament at Grand Tours (tournament mode). One of the character will be replaced with Enel. Defeat and win the tournament.
Foxy
Clear event battle with Chopper twice.
Krieg
Clear event battle with Sanji.
Kuro
Clear event battle with Usopp.
Mihawk
Clear event battle with Zoro under the very hard difficulty setting after Shanks has been unlocked unlocked. Defeat mihawk with a level 2 special after getting hit with Mihawk's level 2 special to unlock him.
Shanks
Clear event battle with Luffy under the very hard difficulty setting after unlocking Aokiji and Enel.
Smoker
Clear event battle with Luffy.
Very hard mode
Clear hard mode in event battle with more than ten characters.
Alternate title screen
Unlock all the characters to get a new title screen that features everyone.
Alternate costumes for The Straw Hats
After unlocking Shanks and Mihawk, complete the entire move set for all The Straw Hat Pirates in training mode to unlock a third costume for them inspired by the Color Walk books.
After unlocking the third Straw Hat costumes, complete Grand Battle thirty times or Event Battle six times, with each of the Straw Hat crew to unlock a fourth alternate costume.
Marine HQ stage
After unlocking everyone, complete their move lists in training mode. After doing so, destroy all the pillars in the stage. Do this with every character to unlock the stage.
Maxim stage
Clear event battle with Enel.
Davy Back Fight mini-game unlockables
Win the Davy Back Fight min-game the indicated amount of times to unlock the corresponding bonus.
Breaking Krieg's Armor: 29 times
Crash Rush Boxer (the box breaking): 18 times
Donut Race: 10 times
Groggy Ring: 4 times
Sanji & Zoro voice (announcing): 33 times; also need all support character voices unlocked
Snow (getting rid of snow): 26 times
The "Fix" sign: 34 times
Play data
Clear Event battle under the very hard difficulty setting to view the stats for your battle.
Ending movies
Clear Event battle to unlock the ending movie at the "Theater" menu.
Gallery
Clear Event battle to unlock that character's images in the gallery.
Voice collection
Clear Event battle to unlock that character's voice collection at the "Treasures" menu.
BMG select
Clear Event Mode with Mihawk under hard difficulty setting to unlock the "BMG Select" at the "Treasures" menu.