We have stuff like WestBallz vs MuckDuck (after handwarmers, the guy went 'that's 1-0' and then took a game lol), Ginger vs DruggedFox, Envy vs Ice, or InfiniteNumbers vs Everybody at Pound 2016.
But in all those cases, as far as I know, even when names are kinda unknown up until an upset in tournament, they're good players who are certainly legitimate. Like, Scar often talks about 'FalcoMaster' ever since he lost to some guy named Ron at Evo one year. Even though no one knew about Ron, the guy was a ranked player from NC who's actually mad good.
I don't know much about SF, but from the commentary it sounds like that Ryu was just a complete random?
Edit:
So scrub busting isn't as big of a thing in competitive Melee as it is in SF?
Pretty much, no. Having 4 stock matches makes it pretty tough to see big surprises like that.
At lower levels though, I have seen Brawl/Smash 4 players pick up Melee and play in a very low input style, winning just on solid fundamentals.
There's a player called Borp that does something like that if I remember right. Doesn't wave dash and junk.