GOKU VS SUPERMAN

Well, the thing is, he could always have found another sun to sundip in. Goku can't breath in space so he wouldn't be able to follow super-man into a sun since, you know he needs to breath and if there is no air anywhere near super-man he can't instant transmission there either since that'd kill him and thus he wouldn't be able to destroy the sun either.
Superman could then absorb as much energy as he wanted, get back to earth with his broken speed and kick goku's ass.

But well, i always found comparing beings from different universes to be quite silly to begin with. I mean i don't see superman being able to fight TTGL for example, but goku could just instant transmission into the cockpit and kill the pilot.

I don't want to argue about this as you're right, but I do want to clarify a few things;

Any Saiyan can freely travel in space, just as superman would, neither can breathe in space, simply are capable of holding their breath for a long time. It could be argued that goku is incapable because of the fact he wasn't raised in that type of environment. I think the battle would have been a lot more legitimate if they didn't scoff goku off as an idiot that can't see his lifeforce being affected by the sun moving closer in. I don't think goku would have teleported him or try to purposefully fight him in the dark, like the kryptonite it would have been an advantage, but it would have certainly stopped him from firing him INTO the goddamn thing.