The official Pokémon website has announced a new event Pokémon distribution through Pokémon Pass. Players of Pokémon: Let's Go, Pikachu! and Pokémon: Let's Go, Eevee! can visit a participating Best Buy location from November 4th, 2019 until November 14th, 2019 and use the app on their iOS or Android device to get a Mewtwo code.

Get Mewtwo for Pokémon: Let’s Go, Pikachu! or Pokémon: Let’s Go, Eevee!

Visit Best Buy to get a code to bring the Legendary Pokémon into your Kantonian adventure for Nintendo Switch.

There are few Pokémon more intimidating to go up against than the mighty Mewtwo. Pokémon: Let's Go, Pikachu! and Pokémon: Let's Go, Eevee! players can now add this Psychic-type powerhouse to their collection! To get Mewtwo, download the Pokémon Pass app for your iPhone or Android device and visit a Best Buy store November 4–14, 2019.

When you use Pokémon Pass at Best Buy, you will be given a code that can be redeemed in your Pokémon: Let's Go, Pikachu! or Pokémon: Let's Go, Eevee! game. And while you're at Best Buy, don't forget that you can preorder the next big Pokémon games for Nintendo Switch, Pokémon Sword and Pokémon Shield. Both titles launch November 15, 2019, and you'll definitely want to see what's in store for Pokémon Trainers in the Galar region!

Use these steps, along with your code, to get Mewtwo:

1. Launch your Pokémon: Let's Go, Pikachu! or Pokémon: Let's Go, Eevee! game.
2. Select Communicate on the main menu.
3. Select Mystery Gifts.
4. Select Get with code/password, then select Yes to save your game and connect to the internet.
5. Enter your code.
6. Watch as the gift arrives in your game. (Pokémon will appear in your party or your Pokémon Box. Items will appear in your Bag.)

Mewtwo Details:

Games: Pokémon: Let's Go, Pikachu! and Pokémon: Let's Go, Eevee!
Level: 70
Moves: Amnesia, Psychic, Teleport, Recover

Source: https://www.pokemon.com/us/pokemon-news/get-mewtwo-for-pokemon-lets-go-pikachu-or-pokemon-lets-go-eevee/