I have a sort of theory now.
Itachi foretold this. He mentioned that Madara was a shell of his former self and it could be that the zetsu, created by Madara holds some of his intelligence and it's an empty shell to be worn. Maybe Itachi was implying that Madara had warped Obitios mind and was further warped by Madara's shell(the zetsu). He only referenced him as Madara as he was warped by Madara and wore his shell. Remember he had seen Obito's face before.
I'm sure someone can explain it better, but it makes sense in my head. I actually hope we see some flashbacks when Madara is dead and Tobis trying to take control of Akatsuki and maybe even an exchange with Itachi. Would be interesting.
Who fight to Minato at that time? Obito with Zetsu, or Only Obito with his real body(i mean without zetsu.)
this chapter is just so so, but at least it's a bit informative.
A few chapter discussions ago, someone here pointed out tobi had not displayed his indestructible power (blocks blades and such with his arm) since perhaps the kages summit and asked if kishi forgot about it. Well, now we have our answer as to how he did it; by wearing zetsu's body (which allows him to bust through huge boulders if the suggestion this chapter is true).
So, it appears hashirama powers produce two organic types of matter distinguishable in the manga,
1) wood - durable, suppressive, at times nearly indestructible.
2) plant - easily damaged but functions as a substitute for other types of tissue (it constitutes a large portion of tobi's body where human tissue and organs could not regenerate)
*3) lotus/flower - insights here.. http://www.mangashare.com/forums/thr...l-Ye-Bow-Down-!!!
As for the battle with minato, if tobi did not block any attack that would otherwise cause harm then there is no reason to believe he wore the zetsu body except if you wish to believe the body added enough additional surface area and height to give tobi the appearance of a fully grown adult physique. It's also hard to say because there is no description of the tactile feedback of striking the zetsu armor Would minato feel it when he landed rasengan? When he touched tobi with the contract nullification? We also don't know if the armor is permanently resilient or just a technique to active. Lots if questions remain as to zetsu's exact nature.
Something fairly obvious that no one mentioned when the Zetsu swirl armor started wrapping itself around Tobi the White zetsu said "hes a good boy"
This is the exact line he uses when Tobi first appears asking to join Akatsuki after Sasori death, "Tobi is a good boy"
I think we can safely assume that Kishi means for Obito (Tobi) to have been influenced by the swirly Zetsu. How much and whether it's exclusive remains to be seen.