i have been using formation b for a long time out of common sense really its best line up for me.... and i don't see sai replacing anyone i won't even try, ten ten can chase 10 hits makes up for her 3round cd and the only other ninja that could be replaced suigetsu and i would have to check and see if sai gives out more dmg but ten ten is better than sai so its between suigetsu i guess but right off the top i doubt it water element standards also from suigetsu