I know that many legendarys are banned from World Touraments, and the item Quick Claw is too, and the moves Chatter, Dark Void, and Sky Drop. Anything else? I've looked on Bulbapedia, and can't find a full list.
World Tournament? You mean this?
I think you mean VGC tournaments. Look here.
Anyone interested needs no longer to click the link.
The following banned Pokemon as of 2012 VGC's are Arceus, Celebi, Darkrai, Deoxys, Jirachi, Manaphy, Mew, Phione, and Shaymin.
Not sure if this should be a comment....convert to if necessary.