Support Trainer

The Support Trainer feature is a mechanic in Pokémon: Let's Go, Pikachu! and Let's Go, Eevee! to allow co-operative multiplayer during regular gameplay.

While the Nintendo Switch is in TV Mode or Tabletop Mode, Pokémon: Let's Go, Pikachu! and Let's Go, Eevee! are normally played using a single Joy-Con or a Poké Ball Plus. If a second controller (Joy-Con or Poké Ball Plus) that is synced to the Nintendo Switch is shaken at any time during the game, a second player character will appear as a Support Trainer. The Support Trainer is the player character of the opposite gender to the main player's player character, with the same hair color, eye color, and skin tone as the host character, and wears a matching set of clothing.

Trainer Battles
In Trainer Battles, if a Support Trainer is present, the host player and Support Trainer will each control one of the Pokémon from the player's party at once, turning a Single Battle into a two-on-one battle in the player's favor. At the start of battle, the Support Trainer will send out the second conscious Pokémon in the player's party.

Wild Pokémon encounters
In wild Pokémon encounters, the host player and Support Trainer throw Poké Balls together.