Godlike
Elyon (Breath of Fire: Dragon Quarter) vs Ashera (Fire Emblem: Radiant Dawn): Elyon doesn't have MT that I can recall, while Ashera does.
Yuna (Final Fantasy X) vs Citan Uzuki (Xenogears): Citan does get a turn, but he's not so damaging that he could OHKO even if all his attacks landed (which they won't).
Lady (Shadow Hearts: From the New World) vs Orgulla (Xenosaga: Jenseits von Gut und Bose): Oh wow, someone actually spoils Lady. Sealed Throne steals all her stock, which leaves her as merely a decent Godlike, not an amazing one. Meanwhile Orgulla now has two boost gauges to do her ice sword bullshit with.
Killer (Shadow Hearts: From the New World) vs Rubicante (Final Fantasy IV): 25% fire resistance isn't cutting it, Killer.
Heavy
Lady Harken (Wild ARMs) vs Alicia (Valkyrie Profile 2: Silmeria): Alicia doesn't limit-dodge well, and she triggers counters. Harken even resists light.
Geno (Super Mario RPG: Legend of the Seven Stars) vs Oerba Yun Fang (Final Fantasy XIII): Statusblocker... fight! Fang resists instant death obviously. Fog -> Pain is a 2-turn win for Fang, now (Geno doesn't have a 2HKO except maaaybe with Geno Flash x2 which will be sealed by Fog), so Geno has to block silence. But this drops his speed so Fang goes first and has 2HKO damage. Geno can Boost to avoid the 2HKO but he won't OHKO with his one turn thereafter.
Justin (Grandia) vs Lucian (Valkyrie Profile): 2HKOs first.
Middle
Vivi Ornitier (Final Fantasy IX) vs Red XIII (Final Fantasy VII): Heal-locks... though a first-turn Osmose could stave that off maybe? If it does, Vivi wins, since he can heal until trance (and if Red stalls then Vivi goes for status). Anyway, Red just under 60% per swing here, so Osmose needs to cut current MP by a third. Does it? Mm... scaling Osmose against average FF9 PC MP, looks like not quite. Really close!
Odessa Silverberg (Suikoden) vs Edward (Fire Emblem: Radiant Dawn): Probably.
Light
Leonardo (Fire Emblem: Radiant Dawn) vs White Mage (Bravely Default): White Mage is a decent dueller against people who can't heal and who don't have great durability.
Ace (Suikoden III) vs Scarmiglione (Final Fantasy IV): Better slugger.
Marivel Armitage (Wild ARMs 2) vs Labyrinthia Wordsworth (Wild ARMs XF): Power Seal does its thing. Labby wishes XF defences were more potent so I could hype her reducing it to turn 3.