Contract with the Kyuubei is the genjutsu itself.
So the contract seal is well established in the Naruto world;
Obito recognizes it instantly, its task is to separate
person A from
summoning B.
So clearly this is not based on genjutsu but severs connections regardless. Would it work on voluntary summons? No, probably not, Gamabunta isn't being forced to work for Naruto.
And the contract is more than that lol.
Obito uses "art of summoning",
Madara tries to as well.
1. If he breaks the contract, what stops the corpses from attacking Minato anyway, considering even killing the summoner won't do it
There's been 1 documented case of Edo Tensei usage involving consent and that is Orochimaru reviving the Hokage in Part 2. Orochimaru improved upon Tobirama's design in Part 1 and they were still barely conscious, so any Edo Tensei Tobirama summons are going to have inferior abilities to Part 1 Hokage's and less consciousness.
So yeah—the odds of consenting zombies? Not gonna buy it.
2. How can Minato seal Tobi, who is more talented than him, while also being pressured by edo tensei
Lmfao....
Tobirama cannot stop complimenting Minato, man... Lmfaooooooo.
Minato can teleport to his chakra, so shadow clones, kunai, marking the ground, the Edo Tensei, Tobirama, etc. Won't be hard given how quick Tobirama is to praise Minato's skills.
Not to mention all Tobirama did with them is use them to blow up the battlefield. They were not fighters, given his lower mastery of the jutsu. Minato's not having any issue with them.
As I said the victory doesn't matter, the fact that they were constantly fighting on equal grounds is more than enough
It doesn't require Tobirama to be stronger if he wins via a sneak attack though, Shikamaru was not stronger than Hidan but was able to beat him through strategy and prep.
Also, Izuna and Madara were never equals lol.
Tumblr Translator said:
EDIT (15 Feb 2020):
Man, this coronavirus infection is getting scary…
**For full accuracy and to avoid further misinterpretation, the translation of the first sentence of Izuna’s profile REALLY should be:
“Following after Madara in ability (lit. true power, force), Izuna accomplished a great number of military achievements.”
or
“Second to Madara in ability (lit. true power, force), Izuna accomplished a great number of military achievements.”
The nuance I get here, is that Izuna’s power/ability level does indeed come second to Madara’s. There is a difference in ability between the brothers. It is not equal. Near equal, perhaps. But Madara is still superior than Izuna while Izuna was alive.
From the person whose translations were used on Fanverse for the Databooks. They updated the translation specifically because of Tobirama shitposters lmfao.
Full link.