Godlike
Lavos (Chrono Trigger) vs Heat (Digital Devil Saga): If Crying Heavens really is lightning than Lavos just completely wrecks Heat. I don't think it is though, despite the animation. But... still, I think the speed lets him punch through and win? Invading Light may well work here (Heat does kinda lose to stat downs in-game so not inclined to hype him as immune).
Ryu (Breath of Fire III) vs Avalon (Legaia 2: Duel Saga): Having HP-1 helps Avalon some, since he can kill a dragon in two turns, but he's too slow, his first form is useless, and while he's reasonably durable it's not nearly enough to stretch Ryu's resources.
TimeLord (SaGa Frontier) vs Cidolfas Orlandu (Final Fantasy Tactics): Orlandu, if he twinks for HP, has an argument to survive TL's raw damage (depends on the HP average used)... but the problem is that even then, he can only get that much HP by leaving himself vulnerable to ID (or petrify), so TL just uses a bunch of TimeEclipses then finishes with MysticSword a couple times or something.
Heavy
Kuja (Final Fantasy IX) vs Hugo (Radiant Historia): Hmm... I think Hugo 3HKOs, while Kuja 5HKOs. If Kuja gets off a counter though that helps a lot, because Hugo's 3HKO is so low that one Curaga turns it into a 4HKO. Only a 50% chance of that though. If it doesn't happen, Hugo wins unless Kuja has a 5-3... which seems extremely unlikely? If it does happen, Kuja more likely wins... but Hugo could still win if he gets a turn below 25% HP, which is... possible. I dunno. Leaning Hugo slightly. For the record, no way is a MT, enemy-only, unreflectable-in-its-home-game ability reflectable to me; they never are in-game in FF.
Middle
Mystere, who is ABSOLUTELY NOT the White Knight Leo (Lunar: Eternal Blue) vs Ricardo Gomez (Shadow Hearts: From the New World): The type of match that plays to Leo's strengths, yeah, the 20% healing is a huge deal against RIcardo's level of offence and the fact that he plays under a time limit.
Roland (Digital Devil Saga) vs Raynie (Radiant Historia): So uh apparently we don't have stat topic numbers for Roland. Surprising! But I think Raynie has this, even though he resists all her damage, since she can land sleep, which is either instant win (if you allow Change shenanigans) or at worst lets her cast regen, heal to full, and try for a poison+sleep lockdown thereafter.
Alexia Lynn Elesius (Wild ARMs XF) vs Valeria (Suikoden Series): Valeria2 loses (gets 2HKOed), but Valeria1 wins (physically tankier). Valeria is fortunate I tend to vote on S1 for her, since she's forced instead of split-path there.
Rand (Breath of Fire II) vs Snow Villiers (Final Fantasy XIII): Rand offence is wretched, so Snow either runs him out of MP or gets a summon. Definitely don't agree with him being Heavy, though! He has a bunch of losses in this Middle field alone...
Light
Dahna (Grandia III) vs Lilianne Valendorf (Mana Khemia 2: Fall of Alchemy): If Dhyer thinks Lily wins if she blocks the correct status... well, Aroma Materials blocks both of them, so I certainly would make that assumption myself even if I limited MK to blocking only one status from their list.
Tim Rhymeless (Wild ARMs 2) vs Freed Yamamoto (Suikoden II): A Freed critical does kill, so Tim really needs me to just take Freed at his average damage. Or he needs to land Arcana 13 before Freed lands a critical or 3HKOs with non-crits, but that isn't too likely. Not sure how I feel about this. EDIT: While I generally do use average damage for simplicity, in a case like this it's pretty cut and dry how crits vs. non-crits work in this fight, so no reason to pretend that's not the case. In which case the odds are very against Tim winning this fight, 47% chance which is a loss even if I don't give Tim any discredit for trying to win via status.
Kain Highwind (Final Fantasy IV) vs Innes (Fire Emblem: Sacred Stones): Both 4HKO each other, assuming Kain can use Jump with no penalty. But Kain will probably miss once.
Shady Thousand (Wild ARMs 3) vs Draggy (Chrono Cross): Draggy is awful against fire resistance, he barely 5HKOs average with his techs nulled and his regular physicals at -20% power. It gets even worse against Shady, who is somewhat evasive, since CC physical chains get badly ruined against good evade. Meanwhile Draggy is even weak to ice! You have to have pretty ridiculously low Shady respect for him to lose this one.