Heavy
Lyndis (Fire Emblem: Blazing Sword) vs Delthea (Fire Emblem Echoes: Shadow of Valentia)
Lyn is +7 AS vs. average (in Elf's equal XP topic). Delthea is +9 AS vs. average with Fire, or +8 AS vs. average with Seraphim. If we say 0.5 and 3.5 are the doubling thresholds, we end up with a combined threshold of 2 AS, which means Delthea narrowly on the dot doubles with Fire? I think that's a Delthea victory unless Lyn gets lucky on evasion. Lyn has good Luck so her evasion is still decent here at least. Even if doubling hype is discarded, Delthea can just serve with 95 Hit base Ragnarok which OHKOs Lyn.
Hrist Valkyrie (Valkyrie Profile 2: Silmeria) vs Celica (Fire Emblem Echoes: Shadow of Valentia)
PC Hrist loses horribly due to counters. That said, boss Hrist allegedly resists most elements by 50%? Even if that's thrown out, it's pretty tricky for Celica to chip Hrist to 51% HP off her attack & counter then try to OHKO with Ragnarok or something, Hrist is kinda too tanky for that strat to work.
Middle
Lucca Ashtear (Chrono Trigger) vs Machias Regnitz (Trails of Cold Steel)
Lucca can burn through Iron MQ before running out of MP, I'm sure. Yeah, Stone status isn't in CT, but not inclined to let this slip through since there's lots of blocking for relevant enemies in CS2.
EDIT: See Random. Huh, Machias might be Heavy after all, unless Iron's reduction goes down a lot faster than I think it does.
Raynie (Radiant Historia) vs Hilda Goneril (Fire Emblem: Three Houses)
Raynie can obviously go for turn 1 sleep and hope for the best, but let's imagine the other options. It's an initiative headache. They're both average initiative, but Warrior's movement isn't great, and Raynie is up against heavily speed-optimized characters in the stat topic, so inclined to give it to Raynie. She wants to wait, but can't, since Hilda just chips with a Short Axe if Raynie passes. Anyway, Raynie 2HKOs, but if G-Fire & friends are seen as range-2, Hilda wins off Short Axe counter + Iron Axe double. If G-Fire is range 3+, then Hilda doesn't KO with just an Iron Axe double, so Raynie completes her 2HKO first. Since Raynie might have a safe win here, and has a 75% chance win anyway...
Light
Sothe (Fire Emblem: Radiant Dawn) vs Dorothea Arnault (Fire Emblem: Three Houses)
I think Sothe narrowly doesn't double Levin Sword Dorothea here for me (halfshift average, but willing to give him some more levels than the equal XP topic). I'm also inclined to take FE ranges somewhat literally so Dorothea outranges Sothe's counters and regens. Unless he gets Bane turn 1 or something...
Kongol (Legend of Dragoon) vs Soldier (Dragon Quest III)
I'll buy super's argument.
Poshul (Chrono Cross) vs Gen (Child of Light)
Poshul is... kinda tanky? Gen's a character who's good at murdering frail (Paralyze) or poor-damage control (Battle Cry) characters, but CC has good damage control and he apparently wasn't frail, so current kneejerk.