Board Thread:Theories and Speculation/@comment-27916438-20170329044844/@comment-734582-20170329204419

Ravenlot 27 wrote: without it, we could came to the conclusion that even a regular MS may suffice. I think a regular MS is theoretically enough. The problem however is one of power.

A MS user goes nearly blind just manifesting the armored susanoo. You basically need EMS to have any vision left to continue on to the next stages. EMS users were shown to be pretty strong (definitely above kage level), but even so it takes time to learn to manifest a Perfect Susanoo.

Six Paths chakra is a huge power boost, so it makes it much much easier to manifest such a powerful jutsu, especially since it also seems to make casting jutsu easier. In sasuke's case i don't doubt that his Rinnegan accelerated his perfect Susanoo, but Kakashi's case pretty clearly proves the rinnegan itself is not required. The Gokage fight seemed to imply Perfect Susanoo was something Madara had before, and chose not to use against Onoki.