Can your partner Pikachu or Eevee evolve in Let's Go?

No. Your starter partner Pokemon cannot evolve, period. Pikachu won't become Raichu and Eevee won't take any of its evolutions. They get boosted stats and exclusive moves to compensate. If you want a Raichu or Eeveelution, you'll need to catch a second wild one.

What evolution methods exist in Let's Go?

Only three: reaching a certain level, using an evolution stone, or trading. That's it. No friendship evolutions, no held items, no time-of-day triggers, no location-based methods. Let's Go stripped the system down to Gen 1 basics, which makes sense since the Pokedex is limited to the original 151 plus Meltan and Melmetal.

How do you get Meltan and Melmetal?

Transfer a Pokemon from Let's Go to Pokemon GO to unlock the Mystery Box, which spawns Meltan in GO. Catch enough Meltan in GO (400 candies) to evolve one into Melmetal , then transfer it back to Let's Go. You can't evolve Meltan inside Let's Go at all; the evolution only works in Pokemon GO.

Which Pokemon need trading to evolve in Let's Go?

Four: Kadabra, Machoke, Graveler, and Haunter. Same as Red and Blue. Give Haunter to a friend, it evolves into Gengar , they trade it back. No held items needed since the game doesn't have held items at all. Online trading works, so you don't need someone in the same room.

Do Alolan forms evolve differently in Let's Go?

You can receive Alolan forms as in-game trades from NPCs in the Pokemon Center. These Alolan versions use the same evolution methods as their Kanto counterparts: Alolan Vulpix still needs an Ice Stone, Alolan Sandshrew needs an Ice Stone too. The method is the same, just the resulting type changes.

Pokemon Let's Go Evolution Chart

Let's Go simplifies evolution to three methods: reaching a level, using a stone, or trading. No friendship evolutions, no held items, no abilities, no breeding. The roster is 153 Pokemon: the original 151 plus Meltan and Melmetal (evolved through Pokemon GO only). Your partner Pikachu or Eevee cannot evolve.