Brainstorming

[Forsberg]

Tobi pretty much got the DNA of every single Uchicha that were killed in the massacre. (His sharingan stash) Making it possible to recreate the coup D'etat that they once wanted using Edo Tensei.

However they would still be ..zombies.

Tobi, whoever this man is might infact be under the Edo Tensei himself already.
Might have been the first test subject of Tobirama, Orochimaru. However he broke the jutsu like Edo Madara did making him immortal.

Also Tobirama had an imperfect version of EdoTensei. So maybe Tobi had to get help from Zetsu to grasp onto the immortality he had been given.

Doing so might be the only way of granting immortality.

 

[kinghadouken]

Well, any theory about Tobi's true identity is welcome (as long as there's logic into them), since there's no hard evidence that would disprove him so.

And I've already brooded on the theory of him being an Edo Tensei freak as well, so yeah.

 

[ChidoriChimp]

plausible. I honestly have no spercific theory, I just believe that any could be true.