Esmeralda (Octopath) vs Loki (VP1)
Per others.
Rhea (FE3H) vs Myria (BoF3)
No vote since I didn't finish BoF3, but assuming this is specifically "Rhea" and not "The Immaculate One"... Rhea's surely getting wrecked, right? Sword of Seiros parasitic healing that works on counters is extremely annoying a la Orlandu, but her durability is going to be questionable, even with support credit. Pretty much a Radiant Dawn Sephiran situation of "wins easily if you can't OHKO, but OHKOing shouldn't be THAT hard."
If The Immaculate One is legal, then I haven't played Silver Snow, but by reputation she's pretty dirty there. (Her tricks in Crimson Flower don't really translate - buffing allies - plus it seems like she suffers some harsh nerfs. Meanwhile SS Immaculate One has stuff like Miracle + 51 Luck + 4 lifebars, 3 of which have Miracle. Checking, the Luck is "only" 39 on Hard, but even if Myria hits for max damage every time, that's the ability to soak ~5-6 hits. Gets even worse if she can't OHKO.)
Baramos (DQ3) vs Orlandu (FFT)
Block Confuse, yeah. Baramos can go for Blasto expulsion but the odds are bad and I probably wouldn't let him spam that move (he only uses it once every 5 or so turns at most IIRC).
Heavy:
Felix (FE3H) vs Daos (Lufia 2)
Mostly anti-voting Daos, if he can't OHKO then he's eating a looooot of damage from two Felix turns.
Finn (CSH) vs Freyjadour (S5)
The Prince has five shots of full healing, and this is a rare fight I'd be willing to spot some defend hype to him (since CSH characters also have Defend as a crucial part of their arsenal, only fair to let the opposition have it too). Finn's damage is bad and per earlier discussions, I would allow some sort of "CSH enemies start piling up Style over time" so the Prince will eventually build up until he can throw two triple damage Crimson Sky ultimates in a row.
Luminary (DQ11) vs Alicia (VP2)
Inclined to agree with 074 - no Sleep blocker in VP2 means Luminary can buff up, Pep Up, and then do horrible things while Alicia dozes off. Note that if you use Meeple's original interp, Alicia loses for free thanks to elemental resist woes, but Pyro's suggestion of using Gram means that Luminary's good elemental resist is less relevant.
Stella (Brig:LoR) vs Serge (CC)
I'll trust Jo'ou.
Middle:
Lysithea (FETH) vs Squall (FF8)
Squall just OHKOs. He has 1117 damage according to the stat topic if I read it correctly, and there's a damage average of 653, so he hits for around .68 PCHP, which should be fatal vs. Lysithea.
Setsuna (Setsuna) vs Robo (CT)
Robo can't break through. Setsuna could theoretically run out of MP but I doubt it.
Mario (Mario Rabbids) vs Lightning (FF13)
Sylvando (DQ11) vs Nergal (FE7)
Note that DQ11 pseudomagic does indeed ignore defense in its home game. It's just that even given that, Sylvando's damage is awful, but it does have an argument for getting around Nergal's good defense.
If you let Sylvando equip two elemental resistance accessories and use an Act III interp, he should win, as he gets to 100% Dark Resist or something near to it. (2 40% Dark resist accessories, then 10% each on Metal King Shield & Metal King Jacket.) With an Act II interp and accessory messing allowed, it might be more interesting, as Devil's Tail is available in Act II if I recall correctly and is 30% Dark Resist (Dark is the easiest element to resist early), so he can stack 60% resist from accessories, and the baseline resistance will be less too if you care about scaling.
I think I only allow a single elemental resistance accessory, meaning Sylvando can get to 60% resist (which also involves tossing his normal armor for better elemental resist... arguably worth some skepticism there for "rotate armor" tricks). Scaling this vs. 37% default resistance is... also 37% "scaled" dark resistance. This will still cut Nergal's damage significantly. So let's see: Nergal deals 0.8 PCHP damage, which is reduced to 0.50 PCHP damage by the scaled resistance. Sylvando has 0.95 PCHP. So yeah, Sylvando is still 2HKOed under this interpretation. He has to pray that his best ST damage in Finger of Justice doubles and kills Nergal, which isn't TOTALLY nutso if you see it as true ITD and hitting Nergal's bad HP, but... nah. Still, if you see Nergal as having < 0.52 PCHP and see DQ11 as true ITD, or allow double elemental resist accessory stacking, Sylvando does have two potential arguments here. (Doesn't make either of 'em to me, but it's not open & shut.)
Light
Flayn (FETH) vs Cecil (FF4)
Cecil's damage can't be THAT bad to not handle Flayn while doubling.
Primrose (Octopath) vs Noel (SO2)
