Well, Mon-El has improved a lot. Spending several years in the future, living as a superhero, definitely paid off. He went from pretty much losing every single fight he got in, when he was first around, to now being a decently skilled and powerful fighter. The guy was even able to give one of the Worldkillers a decent scuffle in a recent episode, despite them having a physical strength advantage over him. And thanks to 31st century medicine and science, he no longer has his lead weakness either.