Overall, I would say Leftovers is a good option for Umbreon. With Moonlight, it provides plenty of recovery to stall your opponents and deal passive damage. One suggestion to make this work better, I would do Toxic instead of Iron Tail. 75 accuracy isn't that good. Toxic with Moonlight gives plenty of time to stall your opponents out. Also, if you go with my suggestion, swap Shadow Ball for Protect for even more stalling and recovery, but is optional.
Hope I helped!