I read through many of the posts here. The villains definitely outclass the heroes one-on-one. But when you add in the coaches, Professor X could lead the heroes to victory. In my opinion it rests on the following:
1) Could Professor X unleash World-Breaker Hulk? WBH has only been seen a couple times to my knowledge. And I believe it took pretty extreme circumstances to get him there. Jean did not when he fought Onslaught, so I don't know how much of a given this is.
2) Would Professor X do that? In this circumstance, because there is no life on Earth but they are fighting for those lives, perhaps he would. Professor X also brings other advantages, such as syncing up his team's battle strategy.
3) Would Dr. Doom have a counter for it? I mean, the guy did take out the Beyonders. And the Hulk has been drained before. Through magic and tech would Dr. Doom (and Thanos for that matter) be able to counter WBH? Or would they have a psychic dampener that would render the heroes unable to link up with Professor X? With prep, I'm sure they would have such a device.
But prep wasn't stipulated here. So, without prep, I bet heroes could pull it off if the answers to the first 2 questions are yes.
It says weapons and devices.
Thanos used one weapon and stopped Warrior Madness Thor in a matter of seconds.
Between him and Doom, if they wanted, they have weapons that could easily destroy the Earth that they're fighting on.
That would leave:
Thor and Silver Surfer
Thanos, Ultron, Mangog and Doom