Pokémon: Let’s Go Pikachu & Eevee - Every Major Gameplay Detail Revealed
2. PokéBall Plus

The thing that seems to have caught most people’s eyes is the little Pokémon thing that’s going to be released alongside the game. It’s literally a Poké Ball, with a little light and a speaker and thumbstick. Utterly pointless, comically superfluous, but nonetheless very, very cool.
They’ve shown off quite a lot about it already. You can use the thing as a controller in place of a joycon - it presumably has buttons on the back - you can throw it to catch Pokémon and, and, and, you take it outside with a Pokémon in it.
If you don’t remember the PokéWalker from HeartGold and SoulSilver, it was a little pedometer that you could transfer a creature to, take it out with you, and it would gain experience and find items. It was very silly fun and this looks like being an upgraded revisit. It even makes the noises relative to the Pokémon you have trapped inside.