Palace 7 Boss (Persona 5) vs Xorn (Grandia III)
P7 boss too tanky, even baking in party buffs / debuffs. Is there any reason to think Xorn is immune to debuffs? Matarunda (and Debilitate if that wears off) kinda tilts the slugfest. (EDIT: To be clear, this is a form 4->5 formchain assumed, no forms 1-3. )
Berle (Star Ocean: The Second Story) vs Benjamin (Final Fantasy Mystic Quest)
Heal through the invincible phase.
Heavy
Materia Keeper (Final Fantasy VII) vs Camilla (Fire Emblem: Fates)
Elf indicated in IRC chat that FF7 boss's Dexterity is less ridiculous than it looks at first glance (90 Dex!!1!), and Camilla can actually take a hit? That said, I guess whether counter-evading Trine is spammable matters a lot here, since Camilla (at least Wyvern Camilla in the stat topic)'s weakness is magic resistance, and using Hell Combo will trigger a counter. Although it's fine if MK doubles. Gonna assume that MK claims another scalp here, but if Trine spamming is not allowed AND MK doesn't double, Camilla might have a shot. (Also, MK is presumably immune to Savage Blow... could FF7 boss's could be hit by Demi...?) Additional fun thought: you could even argue Trample doesn't apply here?! It is a monstrous quadraped...
EDIT: Double-checked, and heck no to Savage Blow hype. That said, it seems like MK really needs doubling or no-Trample hype after all, so sure, I'll switch my vote.
Makoto Niijima (Persona 5) vs Scias (Breath of Fire IV)
Scias runs out of healing before Makoto does. He has Sleep & Confuse... but... neither of them seem to be very good (they both fall off upon taking damage, and Confuse just makes Makoto start fishing for Sabziaos critz with her physical, not act against her own interests). So it's just a straight-up slugfest. (I mean... I *guess* Scias's best plan is something like "fish for Confuse right before Rakukaja is about to fall off and while Makoto is mildly damaged, have it land, have Makoto attack into a 20% counter chance, finish with Shining Blade. Odds are... not good, though.)
Solo (Dragon Quest IV) vs Ayla (Chrono Trigger)
Solo shouldn't be 2HKO'd, so should survive a double by just spamming HealAll a lot. DQ4r might lose it thanks to the more sane HP balance there, dunno.
Middle
Haru Okumura (Persona 5) vs Tolten (Lost Odyssey)
Is this a match of zero votership? Not sure we have any overlap on voters here... maybe Djinn I guess?!
Anyway, if Ultimate Hit is seen as a "called shot" type move that opponents get warning of, Haru should easily take it since she can just reflect it. Since he has uninspiring damage otherwise, it seems like he gives Haru a turn to set up with Heat Riser, which makes things very bad for Haru's opponents if they can't outspeed her and get a cheap shot in first. So seems like it'd favor of her.
Light
Gilbert Stein (The Legend of Heroes: Trails in the Sky SC) vs Mint Adenade (Tales of Phantasia)
The delay on the grenades is pretty decent IIRC... or, well, would be if Gilbert wasn't a bit of a slug himself. That said, there's something to be said for disrespecting ST Delay on bosses, or seeing it as half/quarter effectiveness, or the like anyway to reflect that it's not QUITE as dominating as it might look... otherwise you have Xorn unstoppable eternal champion of Godlike, etc.
Anyway I think the more important question is if the bot summoning is allowed, and if it is allowed, how much... Mint being one of the only duelers who might not be able to OHKO the scaled bots as they pop out. If some amount of bot summoning is allowed AND she misses the OHKO, she's in trouble... not sure how reasonable the latter is, those bots are truly truly OHKO bait unscaled, so even MINT might manage that mighty feat.
Flonne (Disgaea: Hour of Darkness) vs Jagen (Fire Emblem: Shadow Dragon)
Doubled Holy Arrows surely does the trick.
