To make Eevee evolve into an Umbreon, you have to level it up with high happiness at night.
Chat with our AI personalities
Evolve it at 12 pm
Eevee doesn't have a set level to evolve into Umbreon. All you have to do to evolve it is max out its happiness at night. ~KKMG1
You can get an umbreon by getting an eevee from bill in goldenrod city (in a house) and then you can evolve eevee into umbreon by making it happy and leveling it up at night time.
get an eevee and evolve it into a thunderstone
Train your Eevee at night and with happiness. It will eventually evolve into Umbreon.