I cannot believe people are comparing his to tobi/nagato/edo madara.
The fact is the only people who could stand a chance against him, but still lose by a land slide are is two sons. His direct descendants who received his powers.
From what im reading people are basically saying if nagato/tobi/edo madara had the 10 tails sealed in them, they would aswell be able to create the moon. Ill tell you why those three are nothing compared to the sage.
Firstly all 3 have the rennigan, but neither have fully gained mastery of it and yet all 3 are more or less in the top3, if not deffo top5.
I believe the rennigan has way more abilities than what nagato should us and what he did show us wasnt that impressive in comparison to that of the sage. Same goes to tobi and edo madara.
The sage gaining mastery of the rennigan alone just shoots him up to a god, as i said consdiering the 3 rennigan user alive havent fully mastered it and they are easily the strongest ninja's. A lof of people would ask what do i mean by mastery. Firstly he alone has used the creation of all things technique. The funijutsu he used on the `10 tailed is more or less a rennigan tech. If he does use izanagi which he can, he wouldnt go blind. Until we see tobi,nagato and edo madara, being able to use all 7 elements at will then will i say they are gaining mastery of the rennigan
Now, i believe that if nagato fought the 9 tailed from the start he would win but barely. Now take into consideration that the 9 tails power has been halfed by minato. If its the full 9 tailed fox, i do not believe even nagato can beat it and this is just a portion of the 10 tailed.
Minato died sealing the 9 tails. 3rd raikage came up with a draw against the 8 tailed.
The sage fought, defeated and sealed the 10 tails. This alone is insane. If you at the fact that after sealing the 10 tails he should more or less be dead, but then he used chibaku tensei and selaed its body on the moon.
Also note that, i dont believe anybody can seal the 10 tails in their body. Imagine such chakra levels. How much can your body take, but also you have to gain control of its chakra at all times otherwise its will, will easily overpower your will and chakra. This also shows how much chakra the sage had.
If you add the legendary weapons he had which the gold and silve brothers had, should tell you that, even before becoming a jinchuricki he was a god. The fact that he sealed it in him and was not only alive but capable of controlling its power without losing control says its all.
Fact is not even tobi, edo madara, nagato is on the sage's sons level let alone the sage