There are various Pokémon in Pokémon Legends: Arceus that have some special parameters that allow them to evolve to their next form. If you are looking to get one of the best ice Pokémon in the game, Froslass, you will need first to catch a Snorunt in the Alabaster Icelands. Here is how to get that Snorunt to evolve to Froslass in Pokémon Legends: Arceus.
Before you can evolve a Snorunt into Froslass in Pokémon Legends: Arceus, you need to make sure the Snorunt you have is a female. You can tell this by looking at it in your pack. To the right of its entry will be a gender symbol. If it is purple and pointing to the upper right, it is male. A pinkish-red arrow pointing straight down is female.
When you have a female Snorunt, you just need to obtain a Dawn Stone and give it to her. You can buy one from the Trading Post in Jubilife Village for 1,200 Merit Points. You get Merit Points from trading in Lost Satchels. Another way to come across a Dawn Stone is to ride on Ursaluna and find them hidden around the wild. You can gain any of the evolution stones this way.