I feel like a absolute moron that I forgot about the Galotians and to a lesser degree the Rahn for top fuckers in the galaxy* considering they are my favourite race. Also yer the war question is all out no holds barred battle to extinction with tech so it is mainly going to be fought in space. Though it might be interesting who would win on the ground, tech is allowed but no robot armies because thats just boring. Also if you bring in the Frostwrym it is limited to Frosty itself and 100 kids as that is the condition for the good/bad ending.
*I didn't mean to pun but leaving it in anyway.
Honestly, HONESTLY, I'd still put my money on Frosty. No technology means literally nothing. No clothing, no rocks, no sticks, nothing. The 100 Wyrmlings would probably kick ass in almost all 1v1 fights (except against goo enemies, probably), but that doesn't really matter because they would be instantly overwhelmed by the literal ocean of enemies they'd have to face. However if we were to give the Frostwyrm the ability to fly back to its lair across the sea every now and then so it didn't tire out just from the effort required to repeatedly lift its own arms in order to carve waves through entire armies at once, I really don't see how any of the races could possibly take it down, regardless of their numbers. It flies at speeds WAY faster than anything else in the game, is built like a living tank, its tail, teeth, claws, and wings are all weapons that would just cave through whatever they made contact with like a hot knife through butter, and it can also crush your mind from range with its psionic powers. The only possible way anyone could beat it is if they resorted to World War Z tactics and tried to climb on top of it whenever it swooped down to tear at groups of whatever it's fighting and completely ignored the MASSIVE loss of life that would occur from such a feat, but that's not exactly something that would be easy to coordinate without communication's technology and it would be even harder to convince anyone to actually follow through with considering they're not all mindless zombies that don't care about dying. Even then, if we're giving the Frostwyrm the ability to retreat when it's tired, I fail to see any possible way for any of the races in TiTS to deal with a full-grown dragon going beyblade-mode with its tail.
Obviously this isn't really fair because none of the other races mentioned have gotten a home-field advantage (I always operate under the impression these death battle scenarios are happening in an empty void) and it would need to sleep LONG before it even made a dent in the enemies it was facing without it, at which point it would be easy to overwhelm with raw numbers like a swarm of ants, but it's pretty funny to think about that that one change is all it takes to let the Frostwyrm solo the entire sentient universe at once without technology.
Also, if we are taking home-field advantage into account after all, only a couple of the races in the game have what it takes so survive Uveto's climate without clothing, so there's another advantage for good ol' Frosty.