Two official, in-game activities have been announced for Pokemon Sword and Shield. We now know when the first official competition will be held and which Gigantamax Pokemon will initially appear with a greater frequency. The Galar Beginnings Competition will be held December 6-8, 2019, while people will have a better chance of finding Gigantamax Butterfree in Max Raid Battles between November 15, 2019 and early January 2020.
Nintendo Switch Online members will be able to begin registering for the Galar Beginnings Online Competition on November 15, 2019, and registration will end on December 5, 2019. It will be a Single Battle where all entrants will be scaled up to level 50, with people able to use three of their six Battle Team members. No Pokemon Global Link registration is necessary. Also, some (as yet unspecified) Pokemon will not be allowed to participate. The official website says the results will be announced in December 2019.
As for the Gigantamax Pokemon appearing during Max Raids, three will appear more frequently between November 15, 2019 and early January 2020. (However, Gigantamax Pokemon only do appear during Max Raids rarely.) In all versions of the game, people will see this version of Butterfree more often. Gigantamax Corviknight will appear in Pokemon Shield more often, while Drednaw will pop up in Pokemon Sword.
Pokemon Sword and Shield will be available on the Nintendo Switch on November 15, 2019.