Your browser does not seem to support JavaScript. As a result, your viewing experience will be diminished, and you have been placed in read-only mode.
Please download a browser that supports JavaScript, or enable it if it's disabled (i.e. NoScript).
Can someone tell me how to unlock Chopper and Robin?
To get Robin, simply beat Story Mode with the five characters you unlocked earlier on any difficulty (I used easy).
To get Chopper, you have to beat Hard mode with Luffy.
How about Bon Clay and Crocodile?
