I know Orochimaru was the one to complete it, and how do you know exactly who they can and can not summon? For starters, we've never even seen who Tobirama summoned using the technique. And secondly, just because Orochimaru summoned 2 people, it doesn't mean those are the only people he is capable of summoning.
And I don't understand it... You'll give Kabuto the benefit of the doubt with all of his preparations, yet you'll just say that Tobirama and Orochimaru won't have an army fighting for them? How does that make sense? If you're going to make this a fair fight, then they would all be fully prepared which means all of their Edo Tensei would be ready to be summoned.
And on that note, even if Orochimaru only has Tobirama and Hashirama... Kabuto's strongest summon is telling the 5 Kage, and even showing them, Hashirama's abilities to a lesser degree.. Yet Kabuto's summons who don't stand a chance in hell against Orochimaru, are just going to suddenly beat him when they're losing to a random bunch of fodder-nin? Yeah k.
And who said anything about going against the Manga? Do you honestly think Kabuto had all this time between when Orochimaru died til now to collect all of these DNA samples? Not to mention injecting Orochimaru's DNA into himself and the fight which comes with that... It makes no logical sense for him to have collected it all by himself.
@Prince Charles - They can't kill Kabuto because they need him to end the Edo Tensei jutsu... So no, they aren't trying to kill him.