Godlike
Loki (Valkyrie Profile) vs Atma Weapon (Final Fantasy VI): I see him surviving two shots of Flare, and he can 2HKO with almost anything + Indiscriminate. Might even just be able to one-round due to shaky AtmaWeapon MDef (does by the MF6 damage curve!).
Jessica (Dragon Quest VIII) vs Citan Uzuki (Xenogears): May not be OHKOed depending on Jessica's default build and/or DQ8 damage averages, but even if he is, don't see any reason that sleep blocker + fire shield wouldn't hand this to him. (The only build with a really deadly Magic Burst lacks Twin Dragon Lash to put any non-fire pressure on.)
Riou (Suikoden II) vs GenocideHeart (SaGa Frontier): Mm, damage buffering, not sure how I feel about that. Still, since Riou can't kill before the very first shift, I'm inclined to at least give GH his damage from the second shift, which is Tower.
Dheginsea (Fire Emblem: Radiant Dawn) vs Luca Blight (Suikoden II): Probably. Dheginsea post-defences hovers around an effective 2.5-3 PCHP to me, so he'll probably get off three attacks. That... probably kills Luca, especially if one is Ire. Only 18% means that one may not be, of course.
Heavy
Gau (Final Fantasy VI) vs Jeremy Non (Wild ARMs 4): Jeremy gets two turns. Pooor Gau, one of the only Heavies who can't kill Jeremy in a single turn. At least he lives to see one due to def/evade, but two? Yeah, not buying that.
Mia (Fire Emblem Series) vs Wugui (Shadow Hearts): FE evade against pure status no thanks to that hype, unless the status was highly evade-subject in-game.
Crono (Crono Trigger) vs Garan (Shadow Hearts: Covenant): Crono MDef is pretty bleh, so Garan can 2HKO him with magic. So the question is, does he die to two Rainbow-powered Confuses? That's 0.87 PCHP. Hmm, he might. He can also go for Mind Assault then 2HKO, which is slightly better on average, he only takes 0.84 PCHP. Sure, I think I can buy Garan having that much, if barely.
Middle
Hellion (Suikoden) vs Albel Nox (Star Ocean: Till the End of Time): Confuse works.
Tear Grants (Tales of the Abyss) vs Rudy Roughknight (Wild ARMs): Believe he heal-locks with Phaser, which has lots of uses. Once he gets Fury Shot it's over, and I don't think Tear doubles him enough to kill. Open to arguments.
Canas (Fire Emblem: The Blazing Sword) vs Kahn (Breath of Fire IV): Focus punch borderline OHKOs average, let alone Canas. Kinda makes any drain game he has irrelevant, and like hell I buy him OHKOing (or even 2HKOing, if you see Kahn as below average speed due to a few extra levels).
Light
Franz (Suikoden III) vs Gorudo (Suikoden II): Gorudo pretty bad.
Shana (Legend of Dragoon) vs Riki (SaGa Frontier): Yeah sure.
Joker (Suikoden III) vs Solt (Chrono Cross): Solt pretty bad.
Lucia (Shadow Hearts: Covenant) vs Leonardo (Fire Emblem: Radiant Dawn): Lucia buffs herself with Rage, giving her a leg-up on speed, then 2HKOs before Leo 3HKOs her.