Ice is Nice
Nel (SO3), Articuno (PKMN), Marle (CT) vs. Shu (Atl), Hallec (S3), Worker 8 (FFT): I imagine they can stop Hallec from doing anything too nasty, and the healing/revival is a problem for the other team too? Don't know Shu too well, so do argue. W8's spoiling at the end is pretty mean, but with all the healing/revival he should fall.
Nel (SO3), Articuno (PKMN), Marle (CT) vs. Gilgamesh, Artea (Lufia2), Rose (Lod): Gilgamesh goes first and puts Nel to sleep, Arti can't stop Rose from getting a turn... let's say Artea + Rose kill Marle. Articuno MUST use its turns to kill Rose, but there's more Gilgy status coming.
Nel (SO3), Articuno (PKMN), Marle (CT) vs. Yuna, Auron: This team is stupid overpowered, Auron is a great teammate for Yuna due to initiative Threaten and Sentinel. Anima eats through them.
Nel (SO3), Articuno (PKMN), Marle (CT) vs. Asgard, Zero, Ziggy, Gadget Z: Gut says that Asgard's MT ID causes some major problems here. Nel can null it, but on average it kills one of the other two, and Zero meanwhile can block freeze and thus will likely live to turn 2, unless the enemies entirely focus on him and Marle dies first. So let's say that happens. Ziggy is still doing something kinda useful, Asgard hasn't been hurt yet, I imagine they can probably overpower the team from there.
Ragnarok
Hrist, Ull, Surt vs. Shu (Atl), Hallec (S3), Worker 8 (FFT): Lots of 2HKOing going on here. Ull can even Heal. W8's a pain to deal with at the end if Surt is the only one alive but surely the team can keep that from happening. There are even some really nasty damage potential with Surt's Might Reinforce, since that's MT, but not sure if it's worth it.
Hrist, Ull, Surt vs. Gilgamesh, Artea (Lufia2), Rose (Lod): Gilgamesh against bosses isn't too special, Artea gets 2HKOed by whoever (maybe even OHKOed after a Surt Might Reinforce), Rose probably gets one-shotted by Ull as is (his best move is part-holy)... yeah this is straightforward.
Hrist, Ull, Surt vs. Yuna, Auron: Best-case scenario for the team is that Anima can't one-shot either opponent. However, she still has Zombie Attack (so Ull's heal is out... though mm, you can argue the bosses are immune). IF the relevant bosses are seen as zombie immune and not OHKOed this becomes extremely difficult for Anima to take alone... although Auron can open with Magic Break on Ull and hope Anima 2HKOs through that? Anyway Yuna herself can block fire so isn't too scared of Surt, and if Ull dies before Anima, she can take a hit from Hrist if need be, then summon Ifrit and look to finish her that way.
Hrist, Ull, Surt vs. Asgard, Zero, Ziggy, Gadget Z: Not enough fire immunity here, while Ragnarok is ID immune, so they should roll here.
Team Perfect
Wakka (FFX), Wugui (SH), Alfina (G3) vs. Shu (Atl), Hallec (S3), Worker 8 (FFT): If Hallec and Shu both outspeed the enemy team AND can kill Wugui between them, they have a chance. Wakka can still then blind Hallec while Alfina feeds him overdrive... not sure about what Shu can do here. Thunder Reels does wreck W8 really bad. But... he can also just go for the 2HKO on Wakka, and what exactly can Wakka do about it? Not much. His team's gonna lose if this happens. If Game of Death DOES go off, though, that's the end of both Hallec and Shu, and W8 has to solo the entire enemy team which seems much more difficult. I'm not sure where I see Wugui's physical durability... but probably a bit above the 92% Shu+Hallec do (it's close!). It doesn't help that there are reasons to respect Hallec less than the stat topic does. (His awful move hurts his turn 1 speed/damage in-game almost always.)
Wakka (FFX), Wugui (SH), Alfina (G3) vs. Gilgamesh, Artea (Lufia2), Rose (Lod): Artea has a holy weapon, doesn't he? If so, he + Rose can kill Wugui probably, unless Wakka beats Rose to the bunch and she can't simultaneously block blind and sleep. Oh wait, Gilgamesh statuses Wakka turn 1 with something. Right.
Wakka (FFX), Wugui (SH), Alfina (G3) vs. Yuna, Auron: Yeah, no.
Wakka (FFX), Wugui (SH), Alfina (G3) vs. Asgard, Zero, Ziggy, Gadget Z: Wugui is getting a turn here almost certainly (unless Asgard both quickdraws Wakka AND manages to ID him first try), which means Ziggy and Gadget die. Still, Asgard is quite capable of winning this fight the rest of the way... maybe? He does hate Armageddon. Man, not sure. This fight is too much of a headache for me.
Ragnarok 4-0
Perfect 1-2
Ice 1-3