Yeah what's really going to slow you down is the cost point system. I can't evolve my 5* medals to 6 because I won't have enough cost points to equip them. Kinda lame. We need a more ready supply of Cid medals. At the moment I can only equip 2 6* medals.
derp double post anyways! I'd u had to pick between sora kh2 version a. or black cost rikku to 6 star who would you recommend? since I'll only be able to do one in my keyblade for now I'm sure
Black Coat Riku is definitely stronger and his multiplier blows Sora out of the water. Riku's 6* form goes up to 11 hits with a 2.88 multiplier.(that's not counting max fusion bonuses) He is a powerhouse! However! If you already have other powerful Power medals and you are lacking a strong Speed medal, go for Sora. Materials are easy to come by and his base medal is a common drop from Quest stages. Max fusing him at 6* is a very easy endeavor. Especially right now that it's Speed medal day. Keep in mind that there are better speed medals out there like KH Sora B, Rikku, Yuffie, Stitch, Master Form Sora and so many others. KH Sora A ranks pretty low imho.
TL;DR - If you are in dire need of a Power medal, Riku all the way and vice versa. Having too many of one kind of medal is no good.