Hey mate, spoiler tags.

!Mark fought Conquest twice. In the first fight, it's clear that Conquest is holding back and toying with Mark up until he explicitly states that he isn't anymore, and especially after Atom Eve chars him ("I've got more than enough fight left in me for you, boy"); he's clearly trying. In the second fight, he has even less reason to hold back, as Mark has bested him before and he even expresses his happiness that he's gotten the chance to face Mark again. I don't see how you could interpret Conquest breaking every single one of Mark's limbs and murdering his girlfriend in front of him in the first fight, or him punching Mark's ribs through his back and then ripping his intestines out and twisting them in the second fight, as not taking it seriously. He has no reason not to try and every motivation to give his best, especially in the second fight.