Who tells you he didn't use the Juubi's Chakra as well to accomplish this? The Juubi got snatched from Obito forcefully. But why not using a bit of Juubi's Chakra which was left after he created the Bijuu by splitting that Chakra, to seal it away in the moon? Obito's statement isn't topical. He said Rikudo Sennin sued his last powers on his deathbed to create the Juubi and the moon. Yet we've seen his old self still standing in the middle of the Bijuu's, what shouldn't be the case after wasting the last of his power upon his deathbed.
Nothing tells me he did, its not even implied that he did so. Its just an assumption. From what we know when a Bijuu is extracted from you, residual chakra isn't left behind, and we know that when the Juubi is extracted from you, you are left in a weakened state, yet in this weakened state without the Juubi Rikudo was able to pull something like a moon sized Chibaku Tensei off.
Using the last of his powers doesn't necessarily mean he'd die immediately after doing so.
I think at least when Madara got his second eye he will be on pair with the Rikudo Sennin. Having Uchiha and Senju powers such as the Rinnegan and now the complete Juubi, I don't see Rikudo Sennin overwhelming this. The Rikudo Sennin freed the world from the Juubi by sealing it away in himself. Now he has to face the perfect Jin with Rinnegan and kill him. Madara uses now Onmyoton as well which turns any Jutsu to nothing, this is just the power of the Rikudo Sennin as Madara called it.
-Mentioning the Rinnegan doesn't help your case at all here considering Rikudo is a
much much stronger wielder of the Rinnegan, and he is the first to use it and master it completely.
-None of his powers from Hashirama or his Sharingan are even a factor here since their scale is pathetic compared to what he gets from the Juubi's own power.
-Complete Juubi is the only thing they have in common. Onmyoton is something they both use now, though when it comes to Yin Yang Release, Rikudo's mastery of that element trumps Madara's. Evidence? Creation of All Things.
Having Rikudo's power doesn't mean that he is as strong as Rikudo. Rikudo split his energies in half and gave them to his two sons, Madara is a watered down version of a combination of both sons due to already being a watered down version of the Elder Son, and obtaining the power of Hashirama, the watered down version of the Younger Son. A watered down version isn't going to beat the original. Madara isn't on par or as strong as Rikudo Sennin, not even close. The bold is funny mainly because everything you listed is something Rikudo already has himself, but better (Bar the Juubi and Madara's Sharingan techs along with Mokuton)
