Because he had yet to fight in the series when the game was made, Whitebeard's Gura Gura no Mi Devil Fruit was not known, and so all of his attacks utilize his bisento weapon, accompanied by yellow/white waves of power. This was changed in the 3DS version so that his moveset would utilize his powers.
If Luffy enters the battle after all other Straw Hats are defeated with 100 Shadows in your inventory, Luffy will transform into Nightmare Luffy for either the rest of the battle, or until defeated.
In the European release, Garp's profile incorrectly states that he was a legendary pirate (as opposed to a marine). This is true of both Wii and 3DS versions of the game.