Ok what you want to do is either bring alot i mean it ALOT of megalixer's or alot more elixer's have the ability ars arcanum equipped with sora and before you even fight riku go to olympus cloysseum and go to hercules cup defeat cloud and get the metal choccabo (if you dont have it!!!!) then go to where you fight riku and save 1st!.now you fight riku alone without your freinds (so mean) you don't have to be a high lvl i beat him at lvl 21. do you have a dual shock controller that has a button that says turbo on it? if no your going to have a hell of a time fighting riku!!! if you do hold the turbo button and press o and x (o means circle!!!!) and get ready lock on have scan equipped to and strike him down!!! once you get 2 health bars down he should bring out a very very very bad orb that he uses to transform and strike you now hole square not not not circle srry for the misinfo and move the left analog stick in a three sixty degree angle and you'll roll around in circles and he'll jump in the air and transform again and strike from each direction! and keep doing the instruction i just told ya and then hold x to reapedely strike him he shuold have about 13 of the bar left use ars arcamun to finish him off or use ars arcanum whilst having 6 mp bars and then using elexirs to also easily beating him! well there ya go now beat that damned riku ya little cheater!!! p.s. my gummi ships name is wutsittoya