Board Thread:Theories and Speculation/@comment-3568954-20160822081524/@comment-25122992-20160822102338

Well, a theory about the each Rinnegan having a space-time ability seems pretty plausible to me. Even Hagoromo's ability, which allowed his soul to transcend through the centuries, appear in the living world once and even call there the souls of others (when he summoned all the deceased Kage to return Team 7) could be also linked with the space-time ninjutsu, since after his death Obito stated that chakra is the power connecting the worlds and thus could temporarily go back to the world of living with Kamui and give his MS power to Kakashi.

But this doesn't completely cancel out the theory about the Rinnegan having a unique ability for every user, akin to the different MS having unique abilities. However, Six Paths Technique used by Nagato surely aren't unique for him (since some of the Paths techniques were performed by Obito, Madara and Sasuke) and thus are rather "basic" abilities of the Rinnegan itself. There's also the Limbo shadows of Madara which were never used by anyone else and thus potentially unique only for him.