Fulfill certain conditions in the Battle Coliseum mode to unlock these characters to use within that mode. Some characters have multiple conditions to fill; in this case the different conditions will be separated with a semicolon. Conditions involving winning matches with certain characters can be done with or without a teammate. There are 18 characters in total to unlock.

Unlockable	How to unlock
Ace	Win 5 Battle Royale matches; Successfully perform a Link Attack with any characters.
Brook	Win any two matches with Sanji and a female teammate.
Chopper	Reach Rank 1 in C League.
Franky	Successfully counter 6 times in total with Zoro.
Nami	Win two Duel matches.
Robin	Win any two matches with Nami.
Sanji	Get promoted to B League.
Usopp	Reach Rank 1 in C League.
Zoro	Get promoted to B League.