You guys are forgetting Madara was still recovering from the 8 gates when Naruto came in.
No one is forgetting that. But the same can also be said for Naruto and Sasuke as well. Just look at them over the last couple chapters. Even after their revival, their bodies were still scuffed up. You could plainly see that they weren't fully healed. So if you want to say that Madara wasn't fully healed, then acknowledge that they weren't either.
That being said, Naruto completely owned Madara, and he did that even before activating his Rikudo Mode (the Bijuu Chakra Cloak). Sasuke's body changed as well to the point that he's not even phased by Madara's Chakra Rods. Sasuke also has the very Doujutsu that Madara is trying to gain.
You have Obito who doesn't play around when Fighting
Neither does Naruto or Sasuke. But Madara does. But that's not even important. Naruto and Sasuke already beat this version of Obito, even before their power-up.
and if Madara is actually serious I can see them taking it Mid Difficulty at least.
Madara was plainly serious against Naruto. He realized Naruto had a new power that threatened his own. He went for his best technique. He failed. He got thrashed. And again, that was still before Naruto even powered up (with the Chakra Cloak).
They literally already beat him before the power-up.
Juubito and Juubidara would obviously win. The power of 2 ten tails would far be above what Naruto and Sasuke have now.
1. Naruto and Sasuke already beat the power of the Juubi once when they defeated Juubi (before their power-up).
2. Naruto has the Body of the Juubi/Hagoromo, and it has shown to be superior to either Madara or Obito
3. Sasuke has the eye of the Juubi/Kaguya, and it is the very Doujutsu Madara is trying to attain