Calyrex, the big-headed deer-rabbit Pokémon, is the star of Pokémon Sword and Shield’s Crown Tundra expansion.
Soon after starting your journey in the Crown Tundra, you will encounter Calyrex through the story, though you won’t be able to catch it at this time. You’ll simply have to defeat it as part of the story.
[Warning: The rest of the guide explains the process to catch Calyrex, which includes spoilers for The Crown Tundra DLC.]
With the help of Peony, you’ll be tasked with finding Calyrex. It will eventually show itself to you in a weakened state, asking for your assistance. It will also reveal that there is another part of the Pokémon we didn’t see in any trailers — a steed that the Pokémon rides.
Eventually you’ll be tasked with trading some Dynite Ore, which you get from doing Dynamax Adventures, for carrot seeds. Depending on where you plant the seeds, Calyrex will take on a dual-typing. Planting the seeds in the Old Cemetery will make it ghost-type and planting the seeds in Snowslide Slope will make it ice-type. You can only pick one type, and you won’t be able to get the other without trading.
After Calyrex reunites with its steed, you’ll be able to head north to catch it at the Crown Shrine.