But really who the hell would see an umbreon as an opener and a tank???
actually, as a lead, umbreon doesn't work.
It is a mighty fine tank, and it is commonly used as one as well, but you have to look at common leads.
Common leads include: Metagross, Bronzong, Aerodactyl, Azelf, Flygon, Jirachi, Infernape, Heatran, and Scizor
Metagross, Bronzong, and Jirachi, can all take excessive hits from umbreon, without worry, and dish out a ton of damage to it.
Metagross, Bronzong, Azelf, and Heatran can all set up and explode, before umbreon can kill them.
Flygon, Jirachi, Infernape, and Scizor all frequently carry super effective U-turn, and don't mind taking a hit or two from the dark dog either.
Infernape can OHKO with Close Combat, and kill you without worry, while still being able to set up. (leadape carries fakeout, so it doesn't need to worry about focus sash)
and Aerodactyl, can taunt and set up before you have a chance to do any significant amount of damage.
Make sure you look over your common, and even uncommon threats, and study the metagame before creating a risky team like that. Umbreon can take hits for days from some pokemon, but it isn't top tier because it can't handle even some of the most common threats, mostly due to its poor defensive typing.
if you want a good tank lead (i know it doesn't fit your theme) try Swampert, Hippowdon, Metagross, Dusknoir, Gyarados, or Jirachi