It seems that the English localization team of Pokémon Let's Go Pikachu & Let's Go Eevee has big fans of the Batman franchise, as they included two references to the Dark Knight in the names of the Master Trainers.
The video games in the Pokémon franchise tend to include a lot of text, which means that the various localization teams involved with the series have been able to include pop culture references in the dialogue of the trainers that you battle in each game.
The Pokémon Let's Go games feature a post-story challenge where you can battle against Master Trainers, who each specialize in a single type of Pokémon. You have to challenge these trainers using the same kind of Pokémon (such as only being able to use an Eevee against the Eevee Master Trainer) and you can't use any items in the battle, meaning you can't cheese your way through using Full Restores.
The first Batman-themed Master Trainer can be found in the Rock Tunnel. It's here that you can find Scientist West, who is the Zubat Master Trainer.
Scientist West's name is almost certainly a reference to Adam West – the actor who played Batman in the Batman TV show of the '60s and who still voiced the character in the occasional animated movie before he sadly passed away in 2017.
The second Batman-themed Master Trainer can be found on the Victory Road. It's here that you can find Scientist Keaton, who is the Golbat Master Trainer.
Scientist Keaton's name is almost certainly a reference to Michael Keaton – the actor who played Batman in Tim Burton's Batman and Batman Returns movie, and who is still closely associated with superhero roles to this day, as he played the Vulture in Spider-Man: Homecoming.
If they make more Pokémon Let's Go games based on the different regions of the later games, then will we see more Master Trainers with Batman-themed names? Is it possible that we will see Scientist Bale, the Crobat Master Trainer in Pokémon Let's Go Togepi & Let's Go Smeargle? Is there a Scientist Clooney acting as the Woobat Master Trainer in Pokémon Let's Go Vanillish & Let's Go Trubbish?
Pokémon Let's Go Pikachu & Let's Go Eevee is available to purchase on the Nintendo Switch right now.