How to Evolve Eevee into Umbreon
You cannot evolve the Eevee from the Pokemon: Let’s Go, Eevee! data. Thus, you need to catch an Eevee in the wild to evolve it. Once you have caught a wild Eevee, raise your friendship with it. There are a few ways to do this. You can camp, play, and cook with it. You can fight with it in battle to raise it up. Do not let it faint, as that hurts your relationship. There is an item you can give it called the Soothe Bell which makes it more friendly as well. The most important thing is you need to level up Eevee at night. When your Eevee is friendly with you, and you level it up at night, it will change into Umbreon. It should evolve around Level 23. You can view how friendly your Pokemon is towards you by talking to the kid in the house in Hammerlocke, which is to the right of the first Pokecenter. If he says you are pretty good friends, then Eevee will evolve next level.