As usual, the official website has some additional excerpts. I'll post some I find interesting:
This special Meowth that can Gigantamax can be received as an early-purchase bonus for Pokémon Sword and Pokémon Shield by selecting the Get via Internet option in Mystery Gift from Friday, November 15, 2019, to Wednesday, January 15, 2020.
Note: A Nintendo Switch Online membership (paid) is not required to receive the special Meowth.
Note: The special Meowth cannot evolve.
Similar to the Happy Hour Munchlax they distro'd for Sun and Moon.
If you have play records from Pokémon: Let’s Go, Pikachu! on your Nintendo Switch system, you’ll be able to receive a special Pikachu that can Gigantamax in Pokémon Sword and Pokémon Shield.
If you have play records from Pokémon: Let’s Go, Eevee! on your Nintendo Switch system, you’ll be able to receive a special Eevee that can Gigantamax in Pokémon Sword and Pokémon Shield.
Note: You’ll be able to receive the special Pikachu or Eevee at the Wild Area Station in the game.
Note: The special Pikachu and Eevee cannot evolve.
No word whether or not the demo will count for these, but it counted for Smash, so cross your fingers.
Butterfree’s vast wings can stir up a wind strong enough to lift a 10-ton truck, just by flapping. This wind also scatters poisonous scales around the area, so simply being near this Pokémon is very dangerous.
Meowth loves shiny objects, and when it sees skyscrapers lined with glass, it won’t be able to resist the urge to sharpen its claws on them. This behavior can cause considerable damage, such as wearing down the exterior walls and breaking windows.
Pikachu has become so powerful that now it can produce enough electricity to rival a power plant! However, using this electricity to help power people’s homes seems difficult, as Pikachu can only remain Gigantamaxed for a short time.
The fur around Eevee's neck has become extra fluffy and luxurious thanks to Gigantamax power. Any opponent caught in this fur becomes enamored with Eevee and loses the will to fight.
Gigantamaxing has caused Eevee to become more rambunctious than ever, and it will attempt to play with any opponent. However, it often ends up crushing its opponent due to its massive size.