Like all Pokémon games, when you begin your adventure, the region's professor, Professor Oak, will give you your first starter Pokémon. In these games, however, you don't get an in-game choice of your starter Pokémon but rather it is decided by the game you're playing. You get Pikachu in Let's Go, Pikachu! and Eevee in Let's Go, Eevee!.

Let's Go, Pikachu!	Let's Go, Eevee!

These Pokémon have guaranteed max IVs and their gender is determined when you start the game. They also have much higher stats than the standard Pikachu & Eevee

As these Pokémon are your partner Pokémon, they are with you always. Pikachu will always be on your shoulder and Eevee always sitting on your head. However, when you send them into battle, they will jump off to enter the battle. This is even the case when you're riding other Pokémon

At any time, you'll be able to bring up a menu and interact with Pikachu & Eevee in a similar manner to Pokémon Amie and Pokémon Refresh in previous games. You can also feed them berries. This will increase their affection which will allow for them to get special boosts in battle including increased Critical Hit chance, ability to remove status conditions and hold on in battle.

After you have played with it a lot, it will often activate a symbol to talk to you on the overworld. If you do this, you will receive various gifts from your partner Pokémon and they often depend on where you are when your partner gives you the gift. For example, the Beach Glass item is more likely to be found when you're in a sandy area.