Time Mage (Final Fantasy V) vs Walter (The Legend of Heroes: Trails in the Sky SC)
OHKO, TM checks in at a mere 0.76 PDur according to the topic.
Heavy
Nash Latkje (Suikoden III) vs Sage (Dragon Quest III: The Seeds of Salvation)
Well, if Nash goes for healing, he runs out of healing before Sage runs out of damage, and Sage 2HKOs with magic. So fine, SL it is. Sage gets to resolve one spell before Nash's SL finishes casting... probably 3HKOs afterward. Which is probably more like a 4HKO against Nash evade, maybe even 5HKO. Meanwhile, Nash spends 2 turns on SL, then 3HKOs, and is faster. So 5 turns total, but is faster. Sage can win if he/she continuously hits with their physical and wins in 4 rounds, but nope. (Alternatively, YOLO cast Beat and hope for turn 1 ID.)
Marisa (Fire Emblem: The Sacred Stones) vs Parry (Dragon Quest V: Hand of the Heavenly Bride)
vs. the Killers average, Marisa deals .16 PCHP on non-crits. Parry's good def makes that more like .13 PCHP ("good" defense in DQ games), so that's like an 8HKO, except hey 46% crit rate. And crazy evade. Parry needs to have, like, no crits hit so that he doesn't need to heal, then hope to hit with Kazap twice against excellent evade. Yeah Silencer is gonna kick in before that happens.
Knight (Final Fantasy) vs Martym Noumous (Tactics Ogre: Let Us Cling Together)
Martym's stuff is evadable, so evade buffing does its dark work.
Middle
Chameleon Man (Wild ARMs 3) vs Kaze (Fire Emblem Fates)
I force bosses to attack before PCs in stall situations, since Kaze at least doesn't want to do anything. So Misery -> Kaze counter -> Backstab, repeat until one is dead. Looks like 2 Kaze doubles is ~1.23 PCHP or so... maybe more if CM is seen as vulnerable to Poison Strike (all those status vulnerabilities suggests this isn't crazy). Looks like CM is around ~1.40 PCHP, so actually POIZN STRIKE hype is pretty important here!
EDIT: But apparently CM counter-stance stops the likes of Action Replay, so probably stops Kaze's follow-up attack, which is kinda ruinous for his chances.
White Mage (Final Fantasy V) vs Ylianne (Celestian Tales: Old North)
Barely isn't OHKO'd, then Image.
Light
Setzer Gabianni (Final Fantasy VI) vs Jakob (Fire Emblem Fates)
That shuriken debuff doesn't do a damn thing to Fixed Dice. But range 1-2 counters might turn it? Maybe?! Probably not. Looks like from Pyro's FF6 speed chart that Setzer barely avoids being doubled post-Silver Shuriken debuff.
EDIT: But Setzer damage even worse than I recall, he only 4HKOs here. Surely Jakob can 6HKO back w/ counters & def debuffs.
Riddel (Chrono Cross) vs Aurora (Child of Light)
The good news: Riddel shrugs off Aurora's damage like crazy, elementally resisting it, able to buff herself, etc. The bad news: I have no idea how Riddel kills Aurora back. She like 4HKOs, and has to spend a turn buffing... but Aurora is also slow, while Riddel has high Stamina = psuedo-speed. Oh man, what a fail-fest. I think this is a rare time where ELEVATE DAMAGE comes in handy as the fight actually lasts long enough for it to pay off, along with making Riddel's healing more of a wasted turn. Let's see...
Riddel: .92 PCHP, 1.70 MDur post-buff
Aurora: .84 PDur, .78 MDur
Riddel: Snake Skin -> 4HKO Beatdown = 5 turns to kill. (Or 3HKO Beatdown if elements are allowed -> 4 turns to kill.) +1 turn for 63% healing.
Aurora: Elevate Damage -> 3HKO w/ .73 PCHP buffed damage before reduction. Except ramming into elemental resistance, so more like ~.55 PCHP. So... a slow 4HKO + buffing turn or 5 turns, but that healing turn adds 2 more turns at best, so 7 turns.
Holy crap, Aurora still can't penetrate even the one shot of healing, Riddel wins faster. And that's even ignoring that Elevate Damage expires. Fail.
Kosanji (Suikoden III) vs Io Nitta (Devil Survivor 2)
Kosanji kind of a free win.