The Pokémon Company has kicked off yet another distribution event for Pokémon Sword and Shield. Players in certain European countries, including Belgium and the Netherlands, can visit a participating retailer to receive Dynamax Crystal ☆Sgr6913, which can be used in the game to activate a Max Raid Battle featuring Gigantamax Appletun or Flapple. This event is available only for a limited time, so be sure to take advantage of it before it’s too late.
To challenge this 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, you can walk up to the Pokémon Den and interact with it to start a Max Raid Battle with a Dynamax Pokémon. While Gigantamax Pokémon are appearing more frequently in Max Raid Battles, you’ll sometimes encounter one of them instead of a Dynamax Pokémon. Outside of these special time periods, encountering a Gigantamax Pokémon is extremely rare.
Source: The Pokémon Company