Board Thread:Theories and Speculation/@comment-30323490-20170305205254/@comment-26773508-20170308030920

I don't think Sage Mode is an "external" power. It's mainly a skill-set. Sure, only those with high enough chakra can potentially master it, but that doesn't justify calling SM an external power. Only gifted/talented/hard working shinobi have the potential to grow extremely strong. So does that mean natural talent is also an external power? If I understand it correctly, the OP is asking about those shinobi who became strong through Talent+Training, instead of cheats originally did not belong to them: like a bijuu, borrowed dojutsu, or Hagoromo freebies. I suppose MS is also out because it has the potential to suddenly make you OP even without training (eg: Obito slaughtering the Kiri nin immediately after awakening his MS). Being able to gather a little bit of Natural Energy doesn't suddenly make you OP; you still have to train a lot to use Nature Chakra properly. Hence, SM doesn't fall inside the "cheat" category. And neither does belonging to special clans or having a KKG (except MS, EMS, Rinnegan and Tenseigan).

So this is my list:

1)Gai

2) Hiruzen

3)Tobirama

4) Minato

5) 3rd Raikage

6) The Sanin

7) Onoki/Muu