Did you seriously ask about video games' Goku vs Superman?
There is no true easy answer. Both series arguably relies on things that aren't universally agreed on. It literally goes either way depending on your train of thoughts.
With that said, personally, most solid logic / least awful logic makes Sonic winner.
I'll be blunt VSW Mario is AWFUL. Legitimately one of the most wanked shit here. I literally joined here because I was too tired to watch on sidelines how wanked Mario gets. This weird VS Power Creep has infested many series and Mario is one of them. Luigi has no consistent logic to beat Thor and Mario cannot face Jiren. Some of the old admins tried to use a review to justify Mario being universal, a ******* REVIEW.
VSW is really bad for allowing this to happen.
Base Sonic should be universal based on same logic used on Mario here.
If we go for BIG lowballing, then by bare minimum Mario is not planet level while Super Sonic is and Mario wouldn't abuse his items consistently enough to make him winner most of the time. Technically a monster composite Mario could spam a lot of invincibility items forever, but that is not what Mario would realistically do. Weirdly arguments for Base Sonic being planet isn't that bad, but in fairness its definitely not what Sonic Team intended. But any logic used on lowballing Sonic can be used on Mario as well. Mario being cartoony franchise doesn't help making it consistent.
As for wank, technically Base Mario would beat Base Sonic. They both might be universal but funny enough Base Mario can be wanked to be way faster than Sonic. Except Super Sonic would be immeasurable which is a speed stomp blitz. Tho I guess Pure Hearts might AP stomp that? but shrug.
Really, I recommend doing research on this yourself, this is still not agreed on topic.
The only good thing about VSW Mario is that by it pissing me off I decided to also join here. Unironically this is one of the better Death Battle forums that exists nowadays.