How could Armored Gorilla beat Marshall Gorilla? https://onepunchman.fandom.com/wiki/Armored_Gorilla



We all remember this gorilla in season 1, who seems really weak and lost against Genos.



In season 2, we see him beating Marshall Gorilla in one punch.





It sounded very weird to me. The previous episodes showed the monsters of Orochi very strong, and need S-Class Heroes to beat them.

Marshall Gorilla is the same kind as the Supersado girl. 
But Fubuki needed Tatsumaki help to beat her.





He was followed by Zombieman, an S-Class Hero, who was worried about that Marshall Gorilla, so it means that he's as strong as a S-Class Hero...

So if this Gorilla is so strong, how can that weak Armored Gorilla beat him?
Armored Gorilla looked very weak despite claiming to be extremely strong. This is because he was very quickly and easily beaten by Genos.  Also, Genos looks weak compared to the other human there... Saitama.

However, Genos soon after became an S class hero and clearly deserves that ranking based on his skill level.  So Genos is S class level.  Genos and Saitama are absurdly strong and are ridiculous standards to compare to.

You argue that Marshall Gorilla needed someone on the level of an S class hero to beat them.  I would argue that they need an A class hero or similar to beat them but that doesn't matter.  This episode establishes that Marshall Gorilla should be strong enough to at least defeat most A class heroes.

His easy defeat just shows that Armored Gorilla actually was very strong... he looked weak only because of how amazingly strong Genos and (by extension) Saitama are.

Retrospectively, we should know that he was that strong as Genos's defeat of that laboratory alone was enough to skyrocket him up to S rank immediately. While you may want to attribute that strength to Saitama as Saitama beat Kabuto, the hero association was probably not aware of Kabuto so did not include him in their calculations.