- If you were looking for the board game, see Pokémon Master Trainer.
A Master Trainer (Japanese: マスタートレーナー Master Trainer) is a type of Pokémon Trainer in Pokémon: Let's Go, Pikachu! and Let's Go, Eevee!. They are 153 Trainers who each specialize in a different species of Pokémon from Generation I, plus Meltan and Melmetal. They can be encountered in various locations around Kanto after becoming Champion. Master Trainers wear red clothing and have the icon of their favorite Pokémon in a bubble above their heads. Their Pokémon are high leveled and tend to have a lot of AVs and maximum IVs in certain stats.
Battles with Master Trainers are similar to battles in facilities such as the Battle Frontier or Battle Tree. When the player battles a Master Trainer, they can only use one Pokémon of the same species as the Master Trainer's favorite and neither party can use items other than their Key Stone and Mega Stones in battle. Upon defeating one, their title can be used by the player in Link Battles. While the Master Trainers do not use Alolan Pokémon or Mega Evolution, the player is permitted to use them when challenging their respective Master Trainers. The player's party will be fully restored before and after each battle against a Master Trainer. If the player wins, the Master Trainer can be re-battled the following day; if the player loses, they can speak to the Master Trainer for an immediate rematch. The player can run from a Master Trainer at any time, counting as a forfeit. Master Trainers do not give out prize money when defeated, nor do players black out and pay out money if they lose.
The Master Trainers for Legendary Pokémon, Mythical Pokémon, and Ditto do not battle the player. Instead, they grant the player their title upon showing them a Pokémon of their respective specialty with a high enough CP. These Trainers all have the appearance of a Master Trainer Scientist.
Defeating at least six Master Trainers allows the player to battle Red outside the Pokémon League at Indigo Plateau, who will grant the player the title of Battle Master (Japanese: バトルマスター Battle Master) after being defeated. Earning every Master Trainer title, except for those of Mythical Pokémon, earns the player the title of Grand Master (Japanese: グランドマスター Grand Master).