shelgon:

The latest news for Pokémon Sword & Shield has been released, showcasing Gigantamax variants of Pikachu, Eevee, Charizard, Butterfree and Meowth. 

• Gigantamax Pikachu is obtained when you have save data for Pokémon Let’s Go, Pikachu. Its G-Max Volt Crash turns all Electric-type moves into the move and paralyzes opponents
• Gigantamax Eevee is obtained when you have save data for Pokémon Let’s Go, Eevee. Its G-Max Move is G-Max Cuddle which turns all Normal-type moves into the move and infatuates any Pokémon of the opposite gender
• A Meowth capable of Gigantamaxing is available from launch until January 15th 2020 as a special early bonus gift. Its G-Max Move is G-Max Gold Rush which turns all Normal-type moves into the move and scatters coins over the field to pick up
• Gigantamax Charizard’s G-Max move is G-Max Wildfire which sets up a Fire Spin in addition to doing major damage
• Gigantamax Butterfree’s G-Max Move is G-Max Befuddle does damage and can either Poison or Paraylze the opponent or put it to sleep

Source: Serebii | Trailer 

EDIT: The Gigantamax capable Meowth, Pikachu and Eevee are incapable of evolution