How do you catch dusknoir without trading?

To catch Dusknoir without trading, you need to first evolve a Duskull into Dusclops by leveling it up to level 37. Then, use a Reaper Cloth, which can be found in various locations, such as the Pokémon League or the Tower of Mastery, to evolve Dusclops into Dusknoir. Once you have Dusknoir, you can catch it in the wild if you're playing Pokémon games that feature it, such as Pokémon Legends: Arceus, where it can be found in specific areas during certain times.