Zack Fair (Crisis Core: Final Fantasy VII) vs Yuri Hyuga (Shadow Hearts Series)
Yuri blocks all of Zack's statuses (at a minor stat hit) except for maybe Stop but I'd be inclined to let him block that too (no Paralysis in FF7CC, paralysis blocker in SH2), and Zack's status hit rates are not all that great to me anyway. So. That leaves an MP busting war. Yuri picks his SH2 form, goes first, massively buffs (crucially including speed). So long as Zack's Osmose doesn't totally clean him out, he can switch to Dark and Mind Absorb it all back. I guess there's Osmose Blade hype if Zack ever runs out of MP though? But eh, once Yuri gets his first double he throws in buffed damage as well, Zack must heal, then the next double is deadly. The question is how long this takes, since too long and Zack gets some powerful DMW like massive overhealing or invincibility. Inclined to lean Yuri though since the damaging DMWs are less useful than usual - Yuri can drain it back.
Nailah (Fire Emblem: Radiant Dawn) vs Sanctuary Keeper (Final Fantasy X)
Elf both wins and loses.
Terra Branford (Final Fantasy VI) vs Cidolfas Orlandu (Final Fantasy Tactics)
Cid can get enough HP to barely survive Morph ignore-stupid-shields Ultima I assume, so armor break -> Terra Break.
Light
Mist (Fire Emblem Series) vs Tita Russel (Legend of Heroes: Trails in the Sky)
Tita's getting mauled by a Mist double round 1 but I think she wins anyway. Tita abandons magic against Mist Resistance but her gun isn't that bad a drawback anyway. (And since it's a large area target it avoids ALONDITE COUNTER hype). She can apparently do .66 PCHP to average with basic attack->Cannon Impulse, and Mist's bad defense make this probably a KO to me. That said, I think Tita can win even if she misses the turn 1 KO. Smoke Canister for Blind-> Clock Up to stop being doubled -> use Earth Guard or Vital Cannon -> reapply Canister when necessary. She gives up Cannon Impulse and kills much more slowly this way, and it wouldn't be enough if she didn't have Clock Up to stop the doubles, but she does. Of course, Tita eats 2-3 more Blind Mist hits before she can heal, and I'd let FE10 characters forge for accuracy, and Mist probably 3HKOs Tita, so even one hit is probably deadly, but eh, see above, Tita's got an argument to kill round 1 anyway and it becomes coinflippy afterward. Coinflippy enough that I suspect Mist wins given noshift FE10 laguz in the averages, but I definitely prefer halfshift, so.