Madara's PS gets a senjutsu boost from Hashirama's SM if that means anything. Madara is still the Juubi's jinchuuriki so the Susanoo will have the power of the juubi. Juubidamas would bust through the Susanoo. What is Madara gets an RSM cloak from Naruto?
Not really since I've already taken into account his Rikudo Senjutsu boost that PS gets, far greater than anything Hashirama's Sage Mode could ever grant.
Nope. It'll be normal, with a buff due to Rikudo Senjutsu. He can't put the bijuu in Susanoo like Sasuke did since they are in his body, but if he could do that he'd shit.
Juubidama has to land first, and if Madara uses it in close combat, he obliterates himself too since his PS can't tank them either. Then there's the possibility that Indra's Arrow>Juubidama.
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Big sphere is the largest it possibly is and the large sphere is the smallest that it possibly is. Kakashi was in the Land of Lightning and still felt the shockwaves from the attack despite them being all the way in the Valley of the End. That blast radius is way larger than the Juubi's Bijuu Dama's. Half of that is still larger than anything the Juubi has ever accomplished on panel.
Then there's the fact that the SA's Kurama chakra phoenix was cutting the Juubi's tails, yet Rikudo PS slashes from Sasuke were being blocked by Naruto's tails, and the Juubi tanked it's Bijuu Dama. Unless SA's Kurama Chakra Phoenix is stronger than Rikudo Sasuke's PS slashes that sliced and diced Madara's CT orbs......Lol.
Give him a hypothetical chakra cloak from Naruto, and I'd say he'd be able to win.....depending on it's effect on someone like Madara.
What if the scenario is changed completely to where it's Madara's PS armoring RSM Naruto's Kurama avatar vs Bijuu Susanoo?
Bijuu PS is tiers above the Kurama Avatar, and since Madara's PS already has a Senjutsu boost, it's not gonna get another one from merging with Naruto's Avatar, so he'd lose here too.