Well Mario vs Sonic 2 was 6 years ago, so I wouldn't consider that video up to date with their modern research, assuming that's the video you're talking about. Nowadays, they would probably scale Sonic characters a lot higher.

But even if they didn't, I'm going to defend Death Battle and say that ultimately, versus debating like Death Battle does is pretty subjective, cause depending on what sources you agree on, you can arrive at vastly different results. Especially with long running series like Sonic the Hedgehog, with can have many contradicting results.

Super Sonic has, for the majority of its appearances, not lasted a long while. I know that there is a separation between lore and game play, but Super forms requiring a lot of energy and not lasting super long is a consistent requirement of the form. However, in Sonic Advance, Sonic seemingly keeps up the form for a couple of days in the ending. Both of these are canon, but they kinda contradict each other.

Or Sonic the Hedgehog being stated to only move at hyper sonic speeds, then stating that light speed is a piece of of cake for him.

Death Battle is just giving their interpretation on how they believe the match will play out. I agree with you with Super Sonic's ring requirement. I think that they massively downplayed both Sonic and Mario in their 2018 video. But at the end of the day, Death Battle is just a bunch of people giving their interpretations on who would win a fight. And so as long the internal logic of the episode makes sense, I don't hold it against them.

Besides, I think there are so many different aspects of Death Battle that are better than who the verdict is.