Not really paid attention to anything One Piece so not sure how good this will be but I like DW style games...
Its a great anime (its also one of the few ones that has been on track with out soul destroying filler episodes for over 500 episodes)
Basically its ripe for a conversion to the Dynasty Warriors serieshttp://www.youtube.com/watch?v=E-sgqx88tj0
Main character is basically rubber thanks to eating a fruit that gives people different powers (tying to not use terminology from the series)
The guy standing next to him is his brother that has eaten one that eaten one that gives him fire powers
(The clown one can make his body parts come off and can control them, others have different powers)
One set back is once you eat one of these fruits you become a dead weight in water and sink
Its mostly set on water as the main cast are pirates.
To bad the game isnt 360 bound