Baton Passer - Physical Attacker combo.
What you'll need:
-Umbreon
-Any Pokemon with the move(s): Bullet punch, Quick attack, Aqua Jet, Mach punch, Extremespeed, etc.
Umbreon's Movepool:
-Mean Look
-Wish
-Curse (You can replace this for Work Up, but then this strategy is useless)
-Baton Pass
I use Dragonite for this Strategy.
Dragonite's Movepool:
-Aqua Jet
-Etc
-Etc
-Etc
You might want to pick a pokemon that is a water type, or the type of the move you use to attack to get the STAB. For example, Azumarill does 1.5x the damage of Aqua Jet because it's the same type. Honestly, I'd recommend either a hard hitter like Dragonite ,or Dream World Crawdaunt or Dream World Azumarill.
Umbreon is sent out first. Use Mean Look to trap the Pokemon battling so it cannot swap to a Pokemon with super effective attacks. Then try to use 6 Curses without dying. If you're close, use a wish. Then use Baton Pass to switch to your Physical Attacker. Keep in mind it now has a major boost in attack and defense , but a terrible speed. This is where Aqua Jet comes in Handy. Attack first in every single turn. Its a sweep. Its also quite embarrassing to swept by a weak attack such as that.
I'd pick Curse over Work Up, though. Umbreon is weak to fighting and bug. It is more than likely a physical attack that'll hit you in that category. Curse boosts defense, so it adds to Umbreon's awesome defenses.
As for EVS, I'd recommend:
Umbreon: Impish Nature- Leftovers. - 252 EV In HP and SP.DEF - 6 EVs in DEF.
Sweeper: Adamant Nature- Choice Band - 252 EV In ATT and SPEED - 6 in HP
More coming soon!