So, after binging the Akame ga Kill manga, I got curious about this matchup, mostly because I have trouble placing Esdeath's physical stats beyond "whatever is most inconvenient for Night Raid at this exact moment."

Assume that Ranma's ridiculous resistance to cold lets him no-sell Esdeath's time stop. If she is sufficiently strong enough to oneshot him or no-sell his attacks, then give him the Gekkaja to at least be likely to cut her as well as Akame could.