I've been thinking about getting "Let's go Eevee", but I wanted to check that it's not too hard to choose Eevee's evolution. In Pokémon Go you had to use various nicknames to choose Eevee's evolution, but in other games I think you had to use a specific evolution stone.
If you have to use nicknames like you did in Pokémon Go, then are they the same and what nickname corresponds to which evolution?
If you have to use an evolution stone, then how do you get each evolution stone and how far in the game do you have to be to get them?
If neither of these are the correct way to choose your Eevee's evolution, then how is it done and how hard is it to do?