Thats just the thing, the character progression hasn't been brought about by the original creators. There have been so many renditions of him, he's been practically given every insane power imaginable. And ofcourse Buu Saga Goku vs Original Supes would be a completely unbalanced match, but even taking Goku from a time where his strength or "power level" would rival that of Supes, he'd still win for the sake of having his rigorous Martial training.
Uh...that's because the character has outlived his creators and because he belongs to DC, not the people who made him. To argue that the powers he has today don't count is to argue that Batman is perfectly fine with murdering criminals, because he had no problem doing so in 1940 or whatever. That doesn't make sense, of course. Again, you're trying to pit Goku, at his strongest, against Superman, at his weakest. He couldn't even fly in his original inception. Why would we ignore 74 years of lore and mythology? How is this any different than Goku "training" from DB to the end of DBZ? Should we pit the original Superman against the original Goku and let Supes rip the limbs off of a child?
A Saiyan's growth involves more than just getting beat up and than get stronger afterwards. That is just one of their Racial traits. Another big one is that they just get stronger by fighting. Every fight, whether they win, lose or are currently in makes them stronger. What I intended with that is not that Goku will heal after getting beat up by Supes, that is a big no no with what he is capable of. Instead I meant that if you take Goku from a much future timeline after Dbz, and ignore that Dbgt ever happened, there will come a point when he'll be a match for Superman. If he isn't already.
No, a Saiyan's strength comes from being beaten. The worse off his body is, the stronger he'll be once he recovers. Be it a punch to the face, or a blast through the chest, he becomes stronger because he's taken some kind of damage. They aren't healing during the fight and becoming stronger.
And now you're suggesting we ignore the existing lore and say Goku, from some time off into the future in a series that doesn't exist, would maybe be strong enough to take on Superman. And in the same breath, you're saying Superman should be relegated to the powers he was given in 1938, because it's bull**** that he gets more powerful over the course of 74 years. That doesn't really add up to me. Using your argument, I can easily say Superman's upper limits will only get pushed even further as time goes on, because that's been the pattern since his inception. He's only gotten stronger, and faster, and better in every conceivable way. In this far off distant time period where Goku is stronger than he is at present, Superman will only be that much stronger than him, because again, he is a God. That is his role.
Like I said, with what his power reaches in the end of Buu Saga, Goku's movement using his own energy should have surpassed that of IT. I really don't know all the technical limitations to Light Speed, but if Superman can surpass it using his strength, I assume Goku would be able to as well.
You're not basing that assumption on any form of evidence whatsoever. Saying if Superman can do it, Goku should be able to as well doesn't really make sense because me being able to bench 400 lbs doesn't mean you can. Superman is above and beyond Goku in every conceivable way, including being a genius, and third only to Lex Luthor and Batman.
Well if thats the case, you just can't defeat someone who is, for all intents and purposes, invincible. All the multitude of his creators have basically ended up making an unbeatable character with just one weakness to allow for storytelling. When someone is that unbeatable, why would you even pit him or her against anyone else? Superman abilities don't follow any logic, even in his own universe. So God Mode it is. And the match has been cancelled.
That is precisely the point. Superman is a living God, and can't be defeated. That's why hes the most boring character of all time. The writers have to constantly think of bogus ways to add some kind of conflict to his story. That's the reason for the huge fluctuations in his power. Some writers feel the need to weaken him, to allow readers to empathize with Superman, rather than say, "Oh no. Darkseid is here. I wonder if Superman will lose. Yawn" It's for this reason that the only 2 characters I would pit against Superman in a full on brawl is Sentry and Hulk from WWH. Sentry is essentially a Superman clone, and WWH beat just about everyone with his bare hands. That was the strongest he's ever been to my knowledge in the Marvel Verse.