Gouketsu was by far the strongest monster he had seen
Strongest he had faced, I believe was what he said, which wouldn't include Carnage Mode.
I can buy Base CK being maybe a little weaker than Gouketsu, because of how the story portrays them and due to the VGS.
-CK took doen Genos with two punches while playing around.
-Gouketsu took down a greatly damaged Genos (from fighting Awakened Cockroach and Face Ripper) in just one.
-In the VGS, CK one-shots Genos every time he tries to fight him, based on the laugh we hear we can assume that was just him playing around as well or not taking it as seriously as he would in a properly serious battle.
Being an S-Class hero, Gouketsu had no reason to take it easy with Genos, and that punch was likely pretty serious, if not as strong as Gouketsu deemed necessary for an S-Class hero which would've been a lot, especially when Genos shines within the S-Class when it comes to destructive power.
I'd say Carnage Mode CK should be on the same level if not above Gouketsu, considering Gouketsu's feat on Genos is only a little more impressive than what Base CK did, VGS-wise or within the story.
Gouketsu > CK = Darkshine's AP > Garou's durability against Darkshine initially >= Garou's durability against Rover <= Rover's AP > Base Bang/Bomb
Doesn't Darkshine confirm during their first battle that Bang (and likely Bomb) is above Garou when the two fight?
Not what Orochi said, that's definitely not on EC's profile.
The statement used from Gyoro Gyoro is for Pre-Molting EC, as Bang or Genos alone wouldn't have been enough on their own. Are we to believe Gouketsu would've stood a chance against Bang, Bomb and Post-Gouketsu Genos, or dish out their combo move? I can see only a few non-Orochi/Boros level monsters being able to do that, like Golden Sperm, Rover, ENW and as we saw, EC.
And why does Genos scale to hurting EC when he only aimed at the eyes or the centipede's insides, which are EC's more vulnerable parts? Only Bang and Bomb ever did any damage to his carapace.