Well that answers the question of Sonic v. Flash. Although I guess it was always implied with the names, light being faster than sound obviously. My guess is that Flash is part of the same generation as those other guys, and was the school's best pupil.
Anyway, lol at the fact that he ruined the cells by cooking them, but I love the fact that he even did so. Got to do things with style I guess, haha. I'm glad that did happen though, it's best to keep this dynamic of him trying to best Saitama with constant training and just failing as opposed to pulling a Bakuzan. Monsterism doesn't suit Sonic.
Also, I wonder if getting beaten down by Watchdog Man and then ...'King' (heh) both in the same day is going to push Garou to finally take a monster cell. Same with Sonic, though, I like that his thing is to push himself using his natural talents, but I'm sure eventually he'll go full monster. Although maybe he'll be more of a Light-cord-shadow-boxer type monster who just transformed through some weird nonsensical way.