Board Thread:Naruto Discussions/@comment-34700383-20180829185752/@comment-6769189-20180903003757

Littlegen wrote:

It's implicity stated Ashura awakened "Bodily Chakra" and that is what gave him the ability to combat Indra. Naruto is the only user of Six Paths Sage Mode, it's his own unique form that grans him Six Paths Sage Jutsu. It isn't a widespread method of utilizing Six Paths Sage Jutsu due to the unique circumstance in which he obtained it. The only other method of obtaining Six Paths Sage Jutsu given to us through the Manga and Databook is the use of "Six Paths: Ten-Tails Coffin Seal", becoming the Jinchuriki of the Ten-Tails. There is no third method of obtaining Six Paths Sage Chakra detailed to us. Even the logical assumption of how to obtain it is debunked by the story. Madara who had awakened Six Paths Chakra didn't bloom Six Paths Sage Chakra when he absorbed Hashirama's own Sage Chakra. It isn't even clear wether Kaguya gained it from consuming the Chakra Fruit or becoming one with the Divine Tree. 6 Paths Chakra+Sage mode doesnt automatically result in SP Senjutsu. Sasuke harnessed all the Bijuu chakra in combination with his own chakra but Indra's Arrow isnt SPS.

TT Coffin Seal isnt the only other way to achieve SPS

Hagoromo and Hamura had SPS before sealing the Juubi.