Abstaining on Caius, no stat topic. He's good but it's really difficult to know how good.
Ryu vs. Asgard (WAXF): Ryu can just survive a Barrier Fist, so he can transform and do bad things... except that Asgard can spam Fortress of the Gods to turtle against Ryu's AP. He can only use it 20 times, to be fair, but I doubt it matters. Because if he opens with Barrier Fist (no reason not to), then he can KO Ryu on a double eventually and finish him, most likely. Ryu would totally take this if he had like double the AP, probably, a rare fight where his specifics like that matter!
Ryu vs. Gawn Bradia (WA4): Faster. "I know I ain't the coolest, but..."
Ryu vs. Bugzilla (BD): Standard Ryu win. Despite Bug's amazing offence she'll need minimum two turns to down Myrmidon, and Myrmidon's Flame Strikes 4HKO her at worst, and Ryu can afford to transform four times easily. Yep.
Ryu vs. Crazed Eye (MK): Oh hell Cursed Eye gives me a headache. Let's just say Ryu uses his Kaiser Bonebreak here to dodge pretty much all of his limit bullshit.
Ryu vs. Shinryuu (FF5): Even skipping his first turn, Shinryuu gets a turn before Ryu does. I don't think I need to say what happens.
Ryu vs. Zophar (Lunar 2): So Zophar has a bunch of nasty stuff here, mainly MP drains and status, so Ryu... really needs to block those. Unfortunately Protectors and Mind Shield compete over a slot, but let's assume he can scrounge up some Mind Shield + Life Talisman defences so that neither of Zophar's scary moves strike him turn 1. He transforms... and must adopt a status-immune form. Kaiser I suppose. Zophar will of course Fate Storm that. Ryu should get an extra turn in before that happens. Zophar then gets another turn after Ryu detransforms and... at this point successfully lands Status Ball. To avoid this, Ryu needs to pile on more status defence. In that case, we repeat this exercise except Zophar uses his now fully-effective MP draining instead, and after the second Ryu can't do anything. Even with Bonebreak on his Kaiser turn, Ryu falls short. And two MP drains do barely run him out (well, they would leave him with ~11 AP, but he'll use that much transforming).
Ryu vs. Jade (BoF1): Uhhh. God that's a lot of HP to cut through. Let's assume Ryu is faster. Lightning Shadow Warrior is probably the best bet... checking some numbers it has only 130% HP and only Myrmidon's defences, but it still reduces Jade to relying on Chill which is a 4HKO. And Ryu has Warrior speed which is pretty near my TB cap, should 3-2 Jade pretty constantly. So the loop is probably... Ryu transform, then gets in four attacks before Jade kills him, then we repeat. This costs Ryu 45 AP per cycle, and does about 2.85PCHP each time. And then he can get one final attack in, at the very least... yeah I do think that's enough. He HAS to be faster for this to work, though, or BoltX... but I think I'm willing to spot him that. Could be wrong if Lightning Shadow Warrior is impossible, so someone should probably confirm that it is. EDIT: Wait, forgot about Jade's defences. Don't think ~9PCHP is enough any more since it's physical and becomes more like 6PCHP.
Ryu vs. GenocideHeart (Saga Frontier): Outside his one shot of guaranteed Tower GH is relatively fair; this package is what Ryu eats for breakfast.
Ryu vs. Xorn (G3): Xorn being mostly physical does him few favours. His only real hope is to blitz Ryu out at the start of the fight, and I'm not terribly inclined to buy that.
Ryu vs. Yuri Hyuga (SH): Yuri2 these days, which lets Ryu go first. Don't think Yuri can really do too much to Kaiser. Howling, of all things, is a real threat; if I'm reading right then Howling/Howling/Kaiserbreath x2 is a strategy Yuri can't do much about.
Ryu vs. Nene (Blue Dragon): Regular Nene goes first and one-rounds Ryu. Ultimate Nene if he is forced into that... well, Ryu can spoil much of what he does if he nulls both elements and MP damage, so Wildfire or Kaiser. Wildfire is out due to Marble Storm, leaving Kaiser. And... it's possible Kaiser takes this, certainly. The problem is Shadow Bind. I'm not quite sure what Shadow Bind should do as a general thing, but in-game it completely wrecks any PC by separating them from the entity which is the source of their power, and that's a bit too similar to Ryu's dragon genes to me. The fact that his first form wins so cleanly makes this easy.
Lenna vs. Asgard (WAXF): Barrier Fist probably just one-shots her. If she gets a turn, I guess her best bet is to use Slow+Protect to remove any Asgard doubleturns and win from there? But Asgard is accurate enough that I'm not really willing to buy a turn 1 dodge, here.
Lenna vs. Gawn Bradia (WA4): Yup.
Lenna vs. Bugzilla (BD): OHKOs with Exaflare and I don't think anything can stop her from getting a turn to do it?
Lenna vs. Crazed Eye (MK): Whatever.
Lenna vs. Shinryuu (FF5): As with Ryu, Shinryuu is faster. Bad things happen.
Lenna vs. Zophar (Lunar 2): Lenna mocks Status Ball (even if she drops the Ribbon, it only has a 40% chance to do something useful, 20% if Lenna uses a Rainbow Dress) but MP draining is a problem (2HKOs her MP). I think Lenna goes with the Mime setup which slows her down a bit but that's okay... Dualcast/Time/Summon. She takes a hit of MP damage and uses Quick/Meteor/Meteor/Meteor/Return or Mimic. Now, if Zophar finishes killing her MP, she can still Mimic, and at this point she's probably done enough damage to win. She may need to Return a few times to ensure this, but that's fine... if Zophar tries to exploit this by going for Status Ball instead, she essentially buys herself an extra turn which she can use to do whatever with, and all but guarantee that she'll win turn 2. If she sees Zophar going for Fate Storm she can use Carbuncle, which given that WDP works and Fate Storm is unspecial in-game I'm inclined to see working here, YMMV of course. Close fight.
Lenna vs. Jade (BoF1): Well, good news for Lenna is that with diamond equipment and Ribbon she isn't OHKOed by anything Jade does. Of course Ribbon means her resources aren't too great. But... Jade has 65535 MP (thanks Twil!), which means an Osmose Spellblade physical fully restores her MP forever. So... Time/Spellblade, use Regen/Quick to heal, Meteors to do damage, and physicals to restore MP periodically? Slow also hits Jade which really helps, so she'll be able to heal only every two turns.
Lenna vs. GenocideHeart (Saga Frontier): Hm. Lenna needs Carbuncle to block Tower, but she also needs a Ribbon to block the ID/petrify, so she's stuck in Freelancer and can only use one more skillset. Time gives her healing via Regen/Quick, but she surely doesn't have the resources to win any more. Drain Spellblade instead? GH's slash defence always sucks so that should be full healing and... dear god that's embarrassing. GH has NO recourse against a status immune full healer save Tower. Lenna does, admittedly, need to keep up Carbuncle during the entire phase that can use it. Still, seven Carbuncles should be enough, GH durability per phase is not great, and besides that she just cruises.
Lenna vs. Xorn (G3): I think so. Xorn can be slowed and he's fairly physical so hates Protect.
Lenna vs. Yuri Hyuga (SH): Oh hey, status.
Lenna vs. Nene (Blue Dragon): Again, normal Nene just goes first and one-rounds. Ultimate Nene gives Lenna turns which is far more problematic, but again there's Shadow Bind... and again the BD/FF5 parallel is way too strong here, so Nene steals all of Lenna's crystal shards, nukes her MP, and overcomes even Drain Spellblade on a doubleturn if that's her opener. If she tries to open with raw, terrifying offence... that's a better bet, except that Nene does have decent MDef so a one-rounding seems impossible even with Return hype.
Tiz vs. Asgard (WAXF): Asgard can OHKO most Tiz builds, although Feel No Pain will buy him a turn of course... but yeah Asgard's too durable for that blitz especially giving up some Magic boosts for FNP. Alternatively, Tiz survives Barrier Fist with a tank build... but any form which is that much slower than Asgard is just screwed because even with BD's limited speed alteration it'll get doubled at some point.
Tiz vs. Gawn Bradia (WA4): Well, unlike the previous two Tiz can twink to go first! But he can't really stop Gawn from getting a turn... though there's Reraise. Actually, yeah, Reraise 6 times, Gawn runs out of bullets. Alternatively something might be possible with Feel No Pain + a blitz?
Tiz vs. Bugzilla (BD): Yeah, no, she kinda has an answer to most BD bullshit in-game and it shows here. Exaflare or Slaughter does its thing.
Tiz vs. Crazed Eye (MK): Another gut vote of BD being able to backend its damage + Crazed Eye giving me headaches + me not respecting him in-game.
Tiz vs. Shinryuu (FF5): Goes first with Chronothief... but uh not even defaulting will let him survive a turn. And one Godspeed Strike ain't enough. So, Feel No Pain Meteors instead? Those should kill. But... Shinryu also has stone, which Tiz can't block. So no, he does need to go first. But he can, I think, if he takes his Timelord build and uses Speed+30% instead of Feel No Pain.
Tiz vs. Zophar (Lunar 2): Status Ball is gonna wreck, but Tiz can block one thing and make it turn 2. Of course, he can't exactly take out Zophar super-fast, so it's hard to see how he could win this one.
Tiz vs. Jade (BoF1): BD against that kind of HP. No. To top things off I'm not sure how much Tiz can do about even a single BoltX, let alone an entire fight of them.
Tiz vs. GenocideHeart (Saga Frontier): Don't think Tiz can do much about Tower, unlike Lenna or Ryu.
Tiz vs. Xorn (G3): Tiz needs to not get instant doubled and 2HKOed, first of all. Actually, not being 2HKOed is just plain necessary, so no TM build. And Xorn has other nonsense like quick hits. Still, Tiz can clearly get a turn, but... I don't think haste/healing is going to work here, the best he can do is one Slow which should get Xorn down to somewhere above 1.5x average which is still really dangerous. Veil stops the basic physicals but not Dark Hymn, so that's not good enough. Just... don't think Tiz can do enough early, and obviously can't blitz.
Tiz vs. Yuri Hyuga (SH): Timelord with Speed+ again. Honestly, why isn't that the default setup? 20% more speed is obviously worth dropping Meteor's damage from 9000 to 8400, if that's really all Magic does...
Tiz vs. Nene (Blue Dragon): Tiz fully twinked for speed can quickdraw against regular Nene and one-round him, I think? But Ultimate Nene shows up and Shadow Binds him into oblivion again. I'm really not sure how many things I see that working on, so it's funny how the three duellers in this PG all clearly meet the criteria. For all that Tiz has serious problems with Ultimate Nene at best of times, the speed + dispel means him getting faster at all is very difficult and he's badly heal-locked even before Marble bullshit makes things worse.
Lenna 6-5
Ryu 5-6
Tiz 4-7