OK then. We can actually build a deck around this card. Throw a Special Dark and a DCE on Umbreon Prime, and run Espeon MD, Umbreon MD, and Espeon Prime and you'd kick some tail. A nice combo you could use is to run a regular Eeveelution line, with the Eeveelutions from RR, and Undevelop them when they're about to get KO'd. Cloud-Covered Moon and put the card back into your hand. It's flippy, but so is SSU.
Running Eevee MD here with Call for Family is a must. Get the three other Eevee onto your Bench, and evolve each as soon as possible. Uxies will also be needed. I assume Quick Ball and Dusk Ball will see some more play now that Claydol's gone and some consistency will be needed to get a quick start, so those will get your Espeon MD and everything else. If I were to play this deck, I would run:
4-1/2/1/1/1 Eevee MD-Espeon Prime/Umbreon Prime/Espeon MD/Umbreon MD/Flareon RR
The Flareon is used against Dialga G LV.X, because that's gonna be a problem when your Poke-Bodies are shut down and your Espeon MD/Umbreon MD support has been shut down. Otherwise, you'd be covering Umbreon Prime with those cards. If you run Expert Belt, which is definitely recommended, you'd be doing at least 90 damage, given you've attached a Special Dark and a Double Colorless Energy. Add three more Eeveelutions, and that's 120.
The possibility to OHKO multiple Pokemon in the metagame doing this kind of damage is amazing. Consistency in this deck is key, which is why I would prefer someone run two or three Uxie LA. Another idea to start would be the use of a Sableye start. Considering that you'd need to Pokemon Collector, and the fact you'd want to get Sableye out of the Active spot so you can Call for Family or use Signs of Evolution with the other Eevee from Rising Rivals, an Unown Q or two would be necessary.
I think Umbreon Prime has got potential for sure, but being consistent in these times without Claydol is a necessity.