Board Thread:Theories and Speculation/@comment-1512913-20160709202754/@comment-26369387-20160710000750

@UltimaDude Hagoromo had TSB before becoming jinchūriki, too.

@Elveonora Frankly, that part has always been confusing... However, since we're theorising, since part of requirement to use Six Paths — Chibaku Tensei are seals of Six Paths Yin Power and Six Paths Yang Power, I'm guessing that maybe they're some form of Six Paths Senjutsu, meaning that at very least Sasuke could use Six Paths Senjutsu in form of Six Paths — Chibaku Tensei. Beyond that... shrugs

As for Kaguya and Toneri, perhaps her fusing with God Tree and him getting Tenseigan(which, if I remember correctly, was linked with Energy Vessel) respectively lets them use Six Paths Senjutsu?