Is umbreon really worth it for someone who isn’t doing as much competitive as they should be doing to have a umbreon on their team?
In-game, Umbreon is okay. It’s a decent Dark type, but it’s outclassed offensively by things like Bisharp and Pangoro, and its inclination to the defensive side just isn’t as useful in-game, where attacking is key. It can also be a pain to level up an Eevee during the night with high enough Friendship, so that’s another thing you should take into consideration. It of course works, like most things in-game, but I recommend a different Dark type, like the aforementioned Pangoro and Bisharp. If you must use it, here’s a set.
Umbreon @ Leftovers Ability: Synchronize - Throat Chop - Quick Attack - Confuse Ray - Pretty much anything else
Hope I helped!