Based on the fact Tony has very, very little info on the entirety of Nova's resources, and the fact that Worldmind can cripple any computer based tech Tony has (including the suit), Nova wins.
They probably have some data, but it's hardly going to be complete, mainly due to Earth's pretty much non-importance in the terms of inter galactic culture.
And any files they do have on the Nova Corps, are not going to cover a huge amount of what Nova can do.
For instance, files on the Corps aren't going to inform Tony of Nova's vast power (and although Nova told Tony he was the last centurian he didn't really show how powerful he was + Tony has lost that knowledge in his reboot), and the files aren't going to tell Tony about the fact Richard has one of the most powerful sentient supercomputers in civilized space in his head.
Although even Tony did know about Worldmind, there's pretty much nothing he could do to prevent being shut down. In Nova #2 or #3 Worldmind easily went through SHIELD's classified data without anyone noticing or being alerted to a security breach, and even talked about how the tech on Earth was extremely limited.
Well, let's say then that Iron-man has full knowledge of Nova's powerset as abilities, as much as let's say, the WM itself before its reboot. Would he have a chance under those conditions?
I think it is a mistake to assume that hacking SHIELD as any indication of the Worldmind's ability to to shut down Iron-man's armor. Guys like Tony and Richards are light years above the standard 616 earth tech, hell they are far above the standard anything tech in the Marvel U... they just don't share it with the rest of humanity. SHIELD isn't the same ball park as Tony Stark, the difference is about as vast as the difference between Daredevil and a SHIELD Agent. It's not really worth talking about in the same sentence.
If Tony doesn't already have measures in place to prevent it, he will after the first time it happens.
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Truthfully I don't read enough Iron-Man to have an opinion on this fight, but the fact that Tony is even mentioned in the same breath as Reed Richards, a man who goes and gathers every version of himself from Alternate Realities for a prep time sit down, is telling. If Tony doesn't have something on par with Wolrdmind, I'd be shocked, and if he doesn't then frankly he doesn't deserve his standing in the Marvel U.
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Reed Richards doesn't have anything on par with worldmind and the time they interacted in the nova series made that quite clear. He behaved like a gruppie around worldmind and for every idea he had WM came up with something better and Richards went: "of course! that's such an elegant and simple solution!". He's out of their league.
Tony has never shown to have the capability to make anything as advanced as the Worldmind. I mean, his most advanced AI from Extremis/Rescue was pretty good by Earth standards, but still was not anywhere near as powerful as WM, which is known as one of the most powerful supercomputers across civilised space.
And tbh, Tony is nowhere near Reed in terms of Reed's crazy feats.
I mean, while they're both smart, Reed (especially under Miller/Hickman) has been pulling off some of the most insane prep/tech feats around. I don't think Tony has done anything comparable to the alternate reality stuff...
Nova would be fighting a petri dish of scientific, genetic, magical and reality warping insanity...if this was his final call to arms. with that much aid.
Plus Reality Gem.
Nova would be in for the fight of his life. He would effectively be fighting a geeks arsenal of Marvel Universe history.
Nova rocks but I'm giving this to Tony....only because of the prep and this forums potential to make the best use of it.