Pokémon as the franchise hasn’t changed its core mechanics much over the years, but Pokémon Legend: Arceus took steps to make even the most basic features look different.
Prior to this game, evolving a Pokémon would involve bringing the species to a set level and simply watching the animation. Legend: Arceus made it something players need to craft from their bags, allowing you to keep an undeveloped Pokémon for as long as you like without needing to constantly animate.
When viewing your Pokémon from the pouch, the new Evolve option will be selectable if you’ve met the requirements to evolve that species to the next stage.
Trade developments / Commodities held
Legend: Arceus has also maintained the use of evolution items, such as Evolution Stones and items favored by certain species. However, as Hold Items have been removed from the game, items that were previously supposed to be held have turned into consumables.
The same is true for Trade Evolution, as players can now obtain a consumable item called Links that will replace the need to connect with other players, allowing Legend: Arceus to be 100 percent complete as a solo experience.
For example, using a Reaper Cloth on Dusclops will get you a Dusknoir for which you previously needed to trade a holding Dusclops item to trigger its growth.
Travel / Time of day
Some Pokémon like Piloswine and Bonsly will still evolve after learning a specific move and then leveling up.
The time of day will also continue to play a large role in the evolution of certain Pokémon species, both when leveling up and using items. One of the coolest examples of combining presence features with the Johtonian Sneasel and Hisuian Sneasel, they require the use of Razor Claw to evolve.
Using the Razor Claw on the Hisuian Sneasel during the day will evolve it into a Sneasler, while you must use the item on the Johtonian Sneasel at night to get the Weavile.
https://dotesports.com/pokemon/news/how-to-evolve-pokemon-in-pokemon-legends-arceus-all-evolution-methods-explained How to evolve Pokémon in Pokémon Legends: Arceus | All evolutionary methods explained