Platinum S
Can it be argued that Platinum Sperm is stronger than Orochi or even Psykorochi because he fought Garou for a certain amount of time?
The very same Garou who, with his blows, managed to damage Sage Centipede and even forced it to use regeneration.
That very Sage Centipede, which according to the story surpasses Psykorochi. The Monster who granted power to Psykorochi sent these two to defeat Saitama. That being witnessed how Psykorochi lost to Tatsumaki without a chance, yet still considered Saitama a greater threat and sent these two to defeat Saitama.
Of course, Garou couldn't damage Sage Centipede's exoskeleton without resonance, but he was still able to damage its face — to the point where it even had to use regeneration. Dealing damage to a monster whose scale far surpasses Psykorochi likely already places Garou above Psykorochi, and Platinum Sperm fought for some time against this version of Garou.