I hope for the sake of this, that those that chooses to debate have at least read some of Captain Atom.
So lets say that Captain Atom took a stroll down into the time stream, meet his other 3 future selves, and there evil self, the energy Crono Mota.
With one goal, to obliterate the world, and that world is the Marvel verse.
First, they take on Marvel Earth. Can anyone in the Marvel Earth stop them. Good guys only.
#2- Bad guys only.
#3 Thanos
#4 Zeus and Odin
#5 Hungry Galalctus with all of his Heralds
#6 Regular Galactus
Also, remember that all the Captain Atom are essentially one in the same, with the same mastery over there powers. Where as Crono Mota is nothing ut an energy cloud version of Atom. Also, all of them has access to the time stream.
Captain Atom has plenty of appearances to know where he stands power level wise on his own; part of the benefits of being in a self titled ongoing series.
Fact of the matter is, he and his pals gets stopped hard at #1.