tl;dr version, main place I disagree with others is on Levin vs. Delita.
Godlike
Yuri Hyuga (Shadow Hearts Series) vs Xorn (Grandia III): If Yuri buffs, he might well be able to stand against full-HP Xorn, although there's a very real risk he just gets blitzed out by Dark Hymn as he tries. But... I don't think he can pile in quite enough damage to bypass a limit; Xorn will use Despair immediately then blitz away from there, I don't think one EC-FE physical followed by one unbuffed move is enough anyway.
Jeb Niglas (Shadow Hearts: From the New World) vs Ryu (Breath of Fire IV): Probably goes first, which lets him adopt some tanky form which does its thing. Jeb is on the durable side for a SH3 boss but I don't think he can outslug Kaiser anyway.
Nailah (Fire Emblem: Radiant Dawn) vs Alternis Dim (Bravely Default): Nailah might take this if her evade were on the right side of 50.
Heavy
Infernape (Pokémon) vs Lulu (Final Fantasy X): Infernape is entirely physical or fire, not what you want here.
Lang (Legaia 2: Duel Saga) vs Margulis (Xenosaga Series): Lang can avoid the worst of Margulis's skillset with a Mystic Art (does >50% Margulis HP), and his regen should keep him afloat in the early stages.
Levin Brenton (Wild ARMs XF) vs Delita Hyral (Final Fantasy Tactics): I definitely think the consensus is wrong on this one! If Levin lands one Cancel Strike he wins, and he gets minimum two chances to do so. Because after he lands one Cancel Strike, he gets another turn, which he uses to walk around to Delita's back and Cancel Strike again, now with great accuracy. And again and again; Cancel Strike can cancel "future" turns, it doesn't just reset the CTB gauge.
Middle
Jessica Philomele (Mana Khemia: Alchemists of Al Revis) vs Beatrice (Wild ARMs 3): Straightforward.
Stocke (Radiant Historia) vs Bowser (Super Mario RPG: Legend of the Seven Stars): Fear's not the most common blocker, but something always seems to go wrong for the King of Awesome.
White Mage (Final Fantasy V) vs Tifa Lockheart (Final Fantasy VII): Too many ways to control the fight at high-HP, and Tifa just isn't impressive without limits.
Lilly Pendragon (Suikoden III) vs Ryudo (Grandia II): Faster? Let's go with that.
Light
Hix (Suikoden Series) vs Labyrinthia Wordsworth (Wild ARMs XF): Faster, 2HKOs first. Labby could try for Attack and Aim Down, but odds are Hix hits at least once in his next two tries anyway (and he might get three?).
Palmer (Final Fantasy VII) vs Rinoa Heartlilly (Final Fantasy VIII): Y'know I tend to think Palmer is a bit underrated by kneejerk... but it doesn't matter, he has no damage variation to avoid a limit and Rinoa is legit enough outside those anyway.
Taloon (Dragon Quest IV) vs Sialeeds Falenas (Suikoden V): Funeral Wind does its thing; even if it doesn't she probably outslugs/outheals.
