Neither, for having ultimate cross universe battles of ultimate destiny goes against Imperial Decree 67. The only known loophole of this is that it happens in a cantina, the winner being decided by who shoots first. So Luke Skywalker and this so called Superman will be detained by Imperial Stormtroopers and sent to the mining facility of kessal, till such time as they see the Emperor's will as law.
Though seriously, Superman just doesn't have enough weaknesses to even make this a fight worth watching. Yes, I know Luke has is own share of opness in EU, but it just isn't enough. Not when you consider all the invulnerabilities to this and that, the whole almost always holding back as he doesn't want to break things..like glasses, people, mountain ranges, reality, etc. Though perhaps a toned down superman, like the one that lost to sub zero would be the sort that may give hope for a more even playing field. Though that defeats the point of superman, and thus you might as well insert someone else instead rather than that watered down excuse for a superman.
