There are a variety of new Pokémon and variant forms that were introduced in Pokémon Legends: Arceus. Some of the new Pokémon are evolutions of existing ones, such as Ursaluna evolving from Ursaring. Teddiursa and Ursaring don't have a new Hisuian form, but there's still a new Pokémon in the evolution line. Other Pokémon have Hisuian evolutions rather than completely new forms, like the three starters in Pokémon Legends: Arceus.
Different forms of Pokémon started with the Alola versions, and Pokémon Legends: Arceus introduced Hisuian forms. Unlike Shiny Pokémon, different forms usually change more than the color scheme. Hisuian Pokémon forms generally have an additional or different type than the original Pokémon. This means that the Hisuian Pokémon will have alternative move pools and different strengths and weaknesses in battle.
Related: Legends: Arceus — Every Hisuian Pokémon That Evolves With Items
Pokémon Legends: Arceus includes 17 Hisuian forms, some of which evolve into entirely new Pokémon. For example, Hisuian Basculin evolves into Basculegion, one of the rides in Pokémon Legends: Arceus. The Hisuian forms vary in appearance from having a few noticeable alterations to looking like completely different Pokémon. Since these new forms are native to Hisui, most of them can't be caught in their original form in Pokémon Legends: Arceus.
The third evolution for each of the starters in Pokémon Legends: Arceus is a Hisuian Pokémon. Rowlett evolves into Decidueye, a Grass- and Fighting-type Pokémon. Hisuian Decidueye's appearance changes in Pokémon Legends: Arceus from green and orange feathers to red and yellow. Typhlosion, which evolves from Cyndaquil, trades its red fire ring for a purple one and becomes a Fire- and
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