Board Thread:Theories and Speculation/@comment-30631705-20161130044038/@comment-25122992-20161130101440

Well, since most of the MS powers are unique for one MS user, only they are able to use their power the best way possible. I mean, nobody aside from Itachi could use Tsukuyomi and nobody aside from Sasuke can use Kagutsuchi. The only means to obtain these techniques for someone else is to get a hand on the eye(s) of the original user, yet all we know that only the original user can use his doujutsu (MS included) with its fullest potential. Technically, Amaterasu is the only case of MS jutsu that can be utilised through the MS of the different users (i.e. through Itachi's right MS and Sasuke's left MS).