[@Kafka Komedy] Given that monsters are arranged in Undertale to increase in overall strength as the human gets closer to escape, then yes, the vast majority of monsters in Genocide mode are going to be OHKOed (likely with titanic amounts of overkill damage) by a human that has taken to obsessively slaughtering them all beyond the first few. And yes, any monster can absorb a human soul to increase their power, as far as I'm aware.