The official Pokémon website has announced that players of Pokémon Sword and Pokémon Shield can encounter Pyukumuku, Pincurchin, and Snom in Max Raid Battles from September 9th, 2022 until September 18th, 2022, at 4:59 p.m. PDT.

Encounter Pyukumuku, Pincurchin, and Snom in Max Raid Battles

Battle these Pokémon in Pokémon Sword and Pokémon Shield Max Raid Battles, and you might encounter a Shiny Snom.

The moon is full and the Pokémon Dens in Pokémon Sword and Pokémon Shield are filled to the brim with lovable Dynamax Pokémon. Until September 18, 2022, at 4:59 p.m. PDT, Pyukumuku, Pincurchin, and Snom will appear more often in Max Raid Battles—lucky Trainers might even encounter a Shiny Snom!

For an opportunity to encounter these Pokémon in a Max Raid Battle, you’ll need to connect your Nintendo Switch system to the internet through Y-Comm or by selecting Mystery Gift in the X menu, then selecting Get the Wild Area News. After that, whenever you see a pillar of light shining from a Pokémon Den, you can walk up to the Pokémon Den and interact with it to start a Max Raid Battle with a Dynamax Pokémon. This event does not affect the Pokémon encountered within Dynamax Adventures.

Source: https://www.pokemon.com/us/pokemon-news/encounter-pyukumuku-pincurchin-and-snom-in-max-raid-battles/