Most people didn't like The New 52 'Captain Atom' series but if you've been reading it, you'll know that this Captain Atom is vastly different from the old Atom. This one is similar to Dr. Manhattan in a lot of ways and is shown to be the most powerful hero in the DC Universe. He hasn't discovered his full potential yet but his matter/energy manipulation abilities are off the charts. He turned an entire squadron of planes into feathers, just like that.
So what if he somehow tore apart the space/time continuum and traveled to the Earth of the Pre-Flaspoint Universe and got into a fight with it's greatest protector, Superman.
Who would win, considering:-
The battle took place in space,just outside of our solar system
Morals on, for the first 15mins
Win by KO or death.
So, who wins and why?
Note:- Those who haven't read The New 52 'Captain Atom', I suggest that you just check it out, at least the first 5 issues anyway (esp. issues 2,3 and 4).