How to get Umbreon in Pokemon GO is pretty unique, and there are a few ways to go about it.
How to get Umbreon in Pokemon GO: Random Evolution
This way is the least reliable, but technically you could do it if you’re feeling lucky. When Eevee evolves, it will randomly evolve into either Flareon, Jolteon, Vaporeon, Espeon, Umbreon, Glaceon, or Leafeon. There is a way to guarantee which one it will evolve into, however! Which brings me to-
How to get Umbreon in Pokemon GO: Naming Trick
If you give your Eevee a certain name, it will guarantee it to evolve into the respective Pokemon when it has eaten 25 Eevee candy. For Umbreon, name it Tamao, and it will evolve into the Moonlight Pokemon. Keep in mind, the naming trick will only work once per name, so be sure to evolve the Eevee with the best stats. There is another way to guarantee your Eevee will evolve into Umbreon-
How to get Umbreon in Pokemon GO: Classically
Pokemon Gold and Silver were the first in the series to introduce time and day/night cycle, and Umbreon and Espeon were among the first Pokemon that could only be obtained at a certain time of day. It is possible to use the same method as the mainline games to obtain Umbreon in Pokemon GO. First, you must walk your Eevee as a Buddy for at least 10km, and then evolve it (still as your Buddy) at night for Umbreon, or during the day for Espeon.
Those are all the known ways to get Umbreon in Pokemon GO. Happy training!
Photo courtesy of Niantic