Which Nintendo Switch game introduced the Galar region's Champion Cup tournament?

Pokémon Sword and Shield introduced the Galar region's Champion Cup tournament.

Pokémon Sword and Pokémon Shield were released for Nintendo Switch on November 15, 2019. Their story takes place in Galar, a region inspired partly by the geography and industrial heritage of the United Kingdom.

The Champion Cup is the major tournament at the end of Galar's Gym Challenge. After completing the Gym Challenge, the player competes in tournament matches before facing the region's Champion. This structure gives the Pokémon League journey a more organized sporting-event presentation than many earlier games.

Sword and Shield also introduced Dynamax and Gigantamax battles, which temporarily enlarge certain Pokémon during battles. The games later received the Isle of Armor and Crown Tundra expansions through the Expansion Pass.