The official Pokémon website has announced that players of Pokémon Sword and Shield can encounter Gigantamax Urshifu (Single Strike Style) and Gigantamax Urshifu (Rapid Strike Style) more often in Pokémon Dens from June 17th, 2022 until June 19th, 2022, at 4:59 p.m. PDT.

Challenge Gigantamax Urshifu in Max Raid Battles

Earn valuable items by defeating this Legendary Pokémon in your Pokémon Sword or Pokémon Shield game.

Big Max Raid Battles against Legendary Pokémon are waiting for you in Pokémon Sword and Pokémon Shield. Until June 19, 2022, at 4:59 p.m. PDT, Gigantamax Urshifu (Single Strike Style) and Gigantamax Urshifu (Rapid Strike Style) will appear more often in Pokémon Dens. Although these mighty Wushu Pokémon won't give you a chance to catch them, you'll be rewarded with valuable items you wouldn't normally receive from Max Raid Battles by defeating them.

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 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.

Source: https://www.pokemon.com/us/pokemon-news/challenge-gigantamax-urshifu-in-max-raid-battles/