Godlike
Persephone (Wild ARMs 5) vs Fou-lu (Breath of Fire IV): Probably. Fou-Lu gets off one almost-full Dark Wave and that really really hurts.
Middle
Ursula (Final Fantasy IV: The After Years) vs Messam Elmdor (Final Fantasy Tactics): Tenketsu should go through Blade Grasp, a la Punch Art. The stat topic doesn't list its damage but I remember it doing more than her physical, so I can't imagine it fails to 2HKO and a OHKO is possible depending on how harsh I feel like being to a post-Orlandu FFT boss without Defence Up.
Light
Chemist (Final Fantasy Tactics) vs Chahn (Cosmic Star Heroine): Chahn's second hyper turn is turn 7, and with it comes a 200 style burst which should kill Chemist in one hit (and if there's any doubt, Silver Bullets buff should push her over the top. So can Chemist kill before then? Not with damage, Chahn just needs to heal once to stop that. With Assassin Dagger? It kicks in turn 5 on average and then the target gets two more turns, which is just barely enough... unless Chahn's Pick-Me-Up Gun is seen as slowing it down. Overall I'm inclined to. Alternatively, if you don't see instant death bypassing desperation, that'd also tilt the scales (I do, however).