Does Kyurem take this with Hax?
Given what was said here....
Both can be surprisingly random with their movesets but by going off wants being shown in canon:
*Alatreon spams a combination of AoE elemental attacks and dragon element infused melee attacks then it will eventually switch forms during the battle.
*Kyurem mainly uses its ranged ice type moves supplemented by either ranged fire or melee electricity (depending on which form it's using) and can change forms depending on the situation.
Kyurem will have some problems, presuming Alatreon is in one-shot range.
If The Original Dragon is an unquantifiable amount into 5-A, then it's a possible one-shot against Alatreon.... Heck, there are still some values where Alatreon could one-shot, lol. We don't know how much it helps.
Though, if Alatreon is just 8 times baseline 5-A, & Original Dragon is an unknown amount into 5-A, what about the "average" within 5-A? The high end to low end ratio would of 5-A is ~6111.5x there's around 3000 values higher than Alatreon's AP, & almost as many that are in one-shot range.
Anyway, as the posts I quoted mentioned, Kyurem's probably leading with Ice & Fire or Electricity.
So, likely moves include:
Glaciate: Normal Kyurem only. Kyurem attacks by blowing freezing cold air at opposing Pokémon. This lowers their Speed stat.
Ice Burn: White Kyurem only. Kyurem surrounds itself in a cold sphere of reddish energy that it then fires off as reddish-purple beams of energy. This may leave the target with a burn or freeze them solid.
Freeze Shock: Black Kyurem only. Kyurem charges up a massive electrically charged sphere of ice before firing it off. This may also leave the target with paralysis or freeze them and part of the surrounding ground.
(As well as Fusion Bolt or Fusion Flare. Plus Icy Wind, Blizzard & Sheer Cold. However, most of said other attacking moves lack notable or reliable effects. I'm not sure how valuable a drop in Alatreon's Speed via Icy Wind is & while freezing is devastating, game mechanics would say it only happens 10% of the time. Not to mention, Alatreon has Fire.)
Imprison: Using a psychic power, Kyurem creates a seal on itself that prevents its opponents from using any moves they share with it.
Kyurem DOES have Imprison, to prevent Alatreon from using any "moves" Kyurem also has, but IDK how likely it is to go for it, & would Alatreon still have options even after being Imprisoned?
Endeavor: Kyurem hits the opponent with a physical blow that reduces their health to match its own.
If Kyurem is that far behind in stamina or that damaged, Endeavor might be useful.
Scary Face: Base Kyurem only. Kyurem makes a scary face at the opponent, lowering their speed.
Are IQ Skills allowed in this match?