0 gauge, no items:
Lethe (FE10) vs. Jagen (FESD): Jagen doesn't double! Still 3HKOs though. Since melee attacks don't increase gauge, this means Lethe never transforms and certainly isn't killing with 2 counters.
Lethe (FE10) vs. Lorenta (VP1): Fire Lance gives Lethe the ability to attack before being hit more than once. Still, doubled Fire Lance does hurt a lot. Lethe transforms on turn 3 and starts beating the hell out of her... as in probably one-rounds. Even if she doesn't she can take one more weakness-hitting hit, I think, since her mdur is now decent.
Lethe (FE10) vs. Rufus Shinra (FF7): Rufus doubles twice then Lethe transforms and he dies. Ranged damage actually isn't what you want here.
Lethe (FE10) vs. Shady Thousand (WA3): Shady's damage is quite a lot better than Rufus'.
Lethe (FE10) vs. Gobi (BoF1): Gobi's quite a lot like Jagen. Only 3HKOs, but that's good enough.
Lethe (FE10) vs. Garland (FF1): Booo people with no stat topics, but gutcheck says he's at least as good as Jagen.
Lethe (FE10) vs. Zahaak (S5): Zahhak is an free win pretty much. I think his midgame form is less horrid but too bad, I vote on his last non-crazy one and that is awful.
Lethe (FE10) vs. Enil (WA4): Enil has two clone attacks before Lethe transforms. The problem is those can't double because Lethe kills them on counters, and they aren't 2HKOing much of anything. After that Lethe transforms and Enil becomes Enil, i.e. can't actually deal damage.
Ena (FE10) vs. Jagen (FESD): As above.
Ena (FE10) vs. Lorenta (VP1): Decent mdur buys her time to transform, and get near magic immunity. Menu Mystic Cross is an okay option but "attack every five turns", really? Ugggh.
Ena (FE10) vs. Rufus Shinra (FF7): This is really close. Rufus gets three turns of free attacks, after which point she's almost dead, then transforms and starts having things like COUNTERS which 3HKO anyway. So it depends if Rufus can kill her on the fourth turn despite tranform bonuses... oh wait, Ena has RENEWAL and that saves her. Wow.
Ena (FE10) vs. Shady Thousand (WA3): Three rounds of Shady attacks beats out Ena regen.
Ena (FE10) vs. Gobi (BoF1): Back to fighters.
Ena (FE10) vs. Garland (FF1): Yep.
Ena (FE10) vs. Zahaak (S5)
Ena (FE10) vs. Enil (WA4): Regen should buy her the time, I think. Doesn't help that Ena clones would have low damage.
0 gauge, Olivi Grass:
Ranulf (FE10) vs. Quistis (FF8): Ranulf only getting 25 gauge from his first turn + Quistis attack means Quistis gets a second turn to finish him. (3HKOs and doubles.)
Ranulf (FE10) vs. Cyan (FF6): If Cyan goes for offence, he... can't 2-round, so Ranulf transforms and eats him. (one-rounds) So he has to charge for something, and doubled Quadra Slam (even if allowed) isn't fatal, while Quadra Slice/Cleave take too long to charge for.
Ranulf (FE10) vs. Emma (WAACF): Arc-en-ciel + Reset forever.
Ranulf (FE10) vs. Regigigas (PKMN): Doubled Giga Impact or something.
Ranulf (FE10) vs. Evil Gaia (G1): No respect for Evil Gaia maintaining a perfect sleep lock, which is what he has to do since after the first sleep/poison spam, Ranulf will have a full gauge ready to OHKO with.
Ranulf (FE10) vs. Igglanova (PS4): Igglanova is slow to get started. That's bad.
Ranulf (FE10) vs. Alenia (S5): 2HKOs Ranulf with MT magic.
Janaff vs. Quistis (FF8): The DL differences between Ranulf and Janaff under this interpreation don't come up here much. Janaff has more (i.e. monstrous) damage, Ranulf has better magic durability. There are a few other small differences but nothing major. As such, same votes everywhere.
Janaff vs. Cyan (FF6)
Janaff vs. Emma (WAACF)
Janaff vs. Regigigas (PKMN): The closest match to flipping, since Janaff is slightly faster and as such aalllllmost isn't doubled to me. But not quite.
Janaff vs. Evil Gaia (G1)
Janaff vs. Igglanova (PS4)
Janaff vs. Alenia (S5)
0 gauge, Laguz Stones:
Nealuchi vs. Rikku (FFX): Tear happens before Rikku gets an overdrive, and it one-rounds her.
Nealuchi vs. Miranda (G3): Low kneejerk respect for Miranda.
Nealuchi vs. Cervantes (FEA): Cervantes 3HKOs, 1-2 range offsets doubles with Cervantes going first. Is he 2-shotted? Your boss durability may vary, but I really doubt it. ... though Nealuchi has lots of evade. Eh, that probably flips my vote
Nealuchi vs. Catiua (TOPSP): Both waste their first turns, but after that the durability difference is too massive.
Nealuchi vs. Chu-Chu (XG): Chu-Chu sucks.
Nealuchi vs. Noel (SO2): Noel sucks.
Nealuchi vs. Labrynthia (WAXF): MDur and evade tilt this Ugly Old Crow's way.
Nealuchi vs. Mustadio (FFT): FFT guns have enough translation issues that I'm willing to spot them respect checks like this. Flying weakness go, Mustadio suddenly 3HKOs going first and Nealuchi is only getting one turn before this happens.
Gareth vs. Rikku (FFX): No doubling along with bad skill means Ire is too far off, so Limit happens first in this case. Poison + Sleep is fatal.
Gareth vs. Miranda (G3): Miranda has her earth magic! Too bad she can't double with it.
Gareth vs. Cervantes (FEA): WHAT IS THIS, CERVANTES DOUBLING?!? Okay. Well, good thing Gareth counters. I would guess Gareth 3HKOs, so call it four turns because he'll miss at some point. This gives Cervantes some seven or so attacks to win with. Is that enough against Gareth pdur? Eh... sure.
Gareth vs. Catiua (TOPSP): OHKOs. This is embarrassing.
Gareth vs. Chu-Chu (XG): I think?
Gareth vs. Noel (SO2): All of Noel's remotely worthwhile damage is MT. Just like in-game, Gareth is very happy this doesn't double him.
Gareth vs. Labrynthia (WAXF): Good -lord-.
Gareth vs. Mustadio (FFT): Mocks puny weak fighters.
Not too shocked that Nealuchi is a better dueller than Gareth. Thank goodness.
15 gauge, no items, pre-transformed:
Ranulf (FE10) vs. Tifa (FF7): Ranulf is back, new and improved! He's actually pretty close to not doubling Tifa with the higher average, but he manages it. He can't chip at all though, so the question is does he one-shot? Ranulf does 91.8% over a double... not quite enough! Bye.
Ranulf (FE10) vs. Miranda (LoD): munch munch munch (one-rounds... barely doubles)
Ranulf (FE10) vs. Titania (FEs): Titania barely isn't doubled. She 4HKOs with a Hand Axe with range supremacy, while Ranulf 3HKOs her back. She goes first, and Ranulf only gets two turns, no doubling = this isn't fatal and he detransforms and is slaughtered.
Ranulf (FE10) vs. Red Mage (FF1): munch munch munch
Ranulf (FE10) vs. Wil (FE7): Well he doesn't one-round, but he is faster, nobody counters, and Ranulf barely has gauge for a second turn.
Ranulf (FE10) vs. Nanami (S2): No doubles, but Ranulf does 2HKO. And counters. Yeah.
Ranulf (FE10) vs. Tim (WA2): munch munch munch
Ranulf (FE10) vs. Nara/Meena (DQ4): MUNCH MUNCH MUNCH
Skrimir vs. Tifa (FF7): Does Skrimir survive a L2? Yeah, seems like it. And his damage isn't so impressive as to trigger a L3.
Skrimir vs. Miranda (LoD): OHKOs.
Skrimir vs. Titania (FEs): Isn't doubled (somehow), can't be run out of gauge before turn 2, 2HKOs.
Skrimir vs. Red Mage (FF1): Faster if auto-transformed (laguz threat range plot).
Skrimir vs. Wil (FE7): Wil sucks.
Skrimir vs. Nanami (S2): Fairly confident here.
Skrimir vs. Tim (WA2): First Aid doesn't let Tim take a second hit, and he can't do anything useful besides First Aid with his first turn. If he could, he'd survive until Hi-Combine and win.
Skrimir vs. Nara/Meena (DQ4): Meena's not OHKOed, but I don't think she can do anything useful. edit: besides running his gauge out in three turns
Skrimir's too good under this interp which overrates the lion gauge. (You go into Stone/Gem mode almost immediately after getting him.) Still feels like he got lucky here on quite a few fights, he's very close to losing to Miranda/Tifa/Tim in particular.
Lyre vs. Meliadoul (FFT): This is a horrendous slaughter, Meliadoul against things she can't break is terrible. Kinda durable but Lyre counters.
Lyre vs. Jude (WA4): Jude has range which helps. Checking Assault Buster against Lyre's FE speed makes it useless, so Silver Launcher time? Or huh, maybe Rapid Assault actually... this arguably stops him from being doubled. Damage is awful but still 5HKOs Lyre, he gets two turns to her one and isn't doubled, running down her gauge like mad... also isn't countered. Even with a miss or two he should be okay.
Lyre vs. Lyon (FE8): Enough respect here. Your bosses may vary.
Lyre vs. Lightning (FF13): Fire weakness should raise Lightning's ravager damage to a two-round... though evade drops that back to a three. Lyre, however, can kill in two rounds. Still, if Lightning goes first, she can empty out Lyre's gauge before her second turn, and by starting her second round quickly she can ensure this, forcing Lyre to use Olivi Grass turn one which costs her a slugfest.
Lyre vs. Frog (CT): Lyre is faster and can somewhat heal-lock, although gauge makes that tricky. She attacks, Frog heals. (6 gauge) Olivi Grass, Frog uses Water. (12 gauge) Olivi Grass, Frog uses Water. (18 gauge) She attacks, Frog uses Frog Squash since otherwise she'll get off a third attack and statistically have a shot at Rend. So does Water x2 + Frog Squash kill? One Water will probably miss... so yeah, hell no.
Lyre vs. Sophia (SO3): Sophia's damage is so terrible that even if Blood Scylla is the best possible damage type she's in trouble here. I could be argued I suppose, but I imagine Rend sees play soon enough, see the Frog progression roughly.
Lyre vs. Tia (Lufia2): Tia pdur is sub-60%. One Lyre double and she's done. Tia has one turn to win, and Lyre's res is quite good so she should stave off a Spark OHKO or a turn 1 sleep easily enough.
Ulki vs. Meliadoul (FFT): Okay, broad strokes time. Ulki is much better than Lyre. (SHOCK). Better damage, better defence, better evade, better gauge. So he'll win any fight she does unless someone exploits his weakness, and a few more.
Ulki vs. Jude (WA4): Jude, however, hits that weakness! And is very accurate when he uses that basic physical!
Ulki vs. Lyon (FE8): Does Ulki win in three hits? It's what he has to do, Lyon will hit him twice in three attempts and 2HKOs. 1.28 pdur... yeah I probably don't see Lyon having that. shrug FE boss gutchecks
Ulki vs. Lightning (FF13): So all that stuff about emptying Lyre's gauge doesn't work here. Ulki kills in two turns and that's that. Evade prevents Lightning from having any hope of a successful Wind blitz.
Ulki vs. Frog (CT): Uh yeah.
Ulki vs. Sophia (SO3): Unlike with Lyre I'm completely confident here. Sophia fails forever at putting on pressure and evade means Ulki may not even need Tear. Also he may well one-shot.
Ulki vs. Tia (Lufia2): Ouch.