This is just what I have so far, and only covers most of the characters.
Some clarifications:
The fight between Senior Cenipede, Royal Ripper, Bug God and Garou was far more even in the webcomic. SC died, the other two took moderate damage (Bug God even says he'd lose alone), and Garou was interrupted during the fight rather than at the start of a more serious battle. Afterwards, Garou stated they were on par with S-Class heroes, despite having just fought Genos and TTM (both are equal in strength), which is supported by RR severing Genos' arm (wc only, it doesn't happen in the manga).
Garou also wasn't weakened when he went up against Genos, although Death Gatling did injure his hands and face slightly. It's also worth noting that Bang and Bomb
held back not to kill Garou.
During the Monster Association fight, Genos made Fuhrer Ugly bleed with a kick, while Gums and BS both tore off his arms. So, I doubt he's very high level among the Cadres. BS is really high-end, though, because he
knocked out an off guard Bomb with a larger fusion, and Sweet Mask could fight on par with both the smaller and larger fusions.
Flashy Flash's rating heavily depends on Garou either referring to his
human or half-human form. For now, I've just rolled with half-human because that's what profiles originally said. Given the language, I think it's his human form, and it's consistent with Darkshine being portrayed as the muscle in their combo.
Scaling chains:
Early Genos / DSK (dry) < G4 Genos = armed Speed-o'-Sound Sonic (likely with some training) = Tanktop Master = Royal Ripper = Bug God = Elder Centipede < Garou << Bang/Bomb (holding back) < Bang/Bomb (full power) < Overgrown Rover < Half-Human Garou << Darkshine << Evolved Garou < Flashy Flash = Sonic (Ninja Arc) = Genos (Psychic Sister/Ninja/Neo Heroes arc) < Genos (Ultimate Hero arc)
G4 Genos < Fuhrer Ugly < Mutated Fuhrer Ugly <<< Bang / Bomb < Overgrown Rover
G4 Genos <<< Bang / Bomb < Black Sperm = Sweet Mask <<< Tatsumaki (Weakened) << Golden Sperm < Tatsumaki (Full power)
G4 Genos << Fubuki < Fubuki (Psychic Sisters) << Tatsumaki (Weakened)
There's kind of a scaling problem here from Darkshine's statement. From what I can tell, he said Bang didn't greatly injure him, implying there was light or moderate damage. That creates an inconsistency with Garou overpowering Rover, unless we just consider Rover a stonewall and half-human Garou about equal to the Bang/Bomb combo.