The Deep Sea King was a very powerful One Punch villain who was able to go up against Genos, Sonic, and several other fighters in back to back battles. That’s a very impressive thing to do but Genos has gotten way more powerful since then. I don’t doubt that he would be able to very quickly take this guy out. One or two incineration cannons should do the trick and the king isn’t quick enough to catch him. Genos wins.