Hints and Tips for One Piece Grand Battle!
(GameCube)

Mihawk: beat very hard with zolo then do it agai, the 2nd time beat him using the secret attack (it doen't have to be full power secret attack)
Mr. 2 bon clay:get all the characters then beat story with them on every difficulty
Then beat story with sanji again on any difficulty then at the credits don't skip them hold L then press AAXA left AXBAXYXARR left.