Board Thread:Naruto Discussions/@comment-27521865-20190624190722/@comment-27973430-20190625071120

Mu taught Onoki how to use dust release which is a kekkai tota, not kekkai genkai, and no one really knows how it works.

It was never explicitly stated so no one here recorded it on his profile, just in the trivia.

Obito didn't give Nagato the Rinnegan, Madara did.

Itachi did that to fool Sasuke and to give him a reason to come and kill him (Itachi) and then after that Sasuke would be lauded as a hero. And Itachi was undercover as a dangerous criminal if the village didn't treat him as such it would have blown his cover.

Hiden just can't be copied. I am not sure why, it most likely has to do with how they are learned.

The clans don't limit the world of Naruto. A lot of the coolest and/or strongest techniques were not limited to the strongest clans. Rasengan, Chidori, Shadow Clones, Eight Gates, Jiraiya's toad techniques, Super Beast Imitating Drawing all of these are not limited to the people of certain clans. It does seem at this point that things are going in the direction of Dragon Ball though as anyone not related to the Otsutsuki are not going to be really relevant fighters though.