Mongul actually is Superman-level in strength, while Flord is... Class 50? Mongul's father beat (or was beating before Supes saved her, in that man who has everything comic) Wonder Woman. Doesn't seem at all a push to me. And Mongul has an extremely potent long range blast that he emits from his chest. Plus he apparently regularly converses with Despero. I'm really arguing more than I thought I would here. I actually can't seem to remember a fight against anyone good that Flord has won. And he's a hero. Heros are supposed to win fights. But his record 1 on 1 against people holding back is about as good as Mongul's facing multiple high-tier foes that actually want to beat him.