The official Pokémon website has announced that from September 17th, 2021 until September 19, 2021, at 4:59 p.m. PDT, players of Pokémon Sword and Shield will be able to encounter Shiny Lunatone and Shiny Solrock in Max Raid Battles.

Seek Shiny Lunatone and Shiny Solrock in Max Raid Battles across Galar

The Meteorite Pokémon are on the rise in Pokémon Sword and Pokémon Shield through September 19.

As we move into a new season, it's the perfect time to watch the rise of the Meteorite Pokémon throughout Galar. Until September 19, 2021, at 4:59 p.m. PDT, Lunatone and Solrock will be appearing more frequently in Max Raid Battles in Pokémon Sword and Pokémon Shield. Lucky Trainers might even encounter a Shiny Lunatone or a Shiny Solrock during this event!

To encounter these Pokémon in a Max Raid Battle, you'll need to connect your Nintendo Switch system to the internet. Then, whenever you see a pillar of light shining from a Pokémon Den in the Wild Area or elsewhere, 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. Whether by night or day, have fun seeking out Lunatone and Solrock in Galar!

Source: https://www.pokemon.com/us/pokemon-news/seek-shiny-lunatone-and-shiny-solrock-in-max-raid-battles-across-galar/