It's Rinnengan Obito without Six Paths of Pain and before he becomes the Juubis jinchuriki!!
Honestly can't see how he'd beat all 5 kages in that situation. Sure thing he has Gedo Mazou, but if the kages just focus him rather than the Gedo I doubt he'd be able to keep up.
I say the 5 Kage wins high difficulty. I don't see Obito taking out all of them by himself. Ay's speed is enough to keep Obito on his toes, Oonoki solos Gedo, Tsunade can take Gedo with her strength. Gaara and Mei is there, who can offer great backup support. I don't see Obito winning, he might be able to kill one of two, but he losses overall.
Obito VS Kages: Kages Win Low Difficulty
Obito & 6 paths jinchurki VS Kages: Obito & Jinchurki Win Mid Difficulty
Obito & Gedo Mazou VS Kages: Kages Win High Difficulty
Scenario 1: Obito is up against 5 Kage level fighters. Most of Obito's techniques are all
fire based attacks. Mei can counter with Suiton Water Style.
Then there's Oonoki's Jinton Obito has to worry about. He will use a lot of chakra
because he will be teleporting and dodging throughout the entire fight. He doesn't
have Susanoo like Edo Madara, who could tank the Kages combined attacks. The
Kage will overwhelm Obito.
Scenario 2: The fight is now 5 VS 7. Each Jinchuriki are linked with the Rinnengan.
They can also power up to their V2 forms whiu will cause trouble for the Kages.
I'm sure the Kages all know sealing techniques but the Jinchuriki in V2 are all fast
an strong. Not to mention they can also transform into their tailed beast forms. If that
happens the Kages have no chance.
Scenario 3: This could go either way. The Gedo Mazou was knocked down by KCM Naruto,
So I'm sure the combined Kages could do some damage to it. But still the odds are in
Obito's favor. As Gedo is a giant and could just step on someone like Gaara and Mei.