I'll list a few:
Mandibuzz
Mandibuzz can take any hit from Umbreon, and prevent it from setting up with Taunt. If your opponent hasn't switched yet, just Toxic stall away.
Terrakion
STAB Choice Band Close Combat is nothig to laugh at, this thing will get the job done.
Azumarill
STAB Choice Band Play Rough will do huge damage to Umbreon even with boosts, or you could even run Belly Drum instead. of CB.
Skarmory
Skarmory can take any hit Umbreon throws at it thanks to its massive Defense stat, and can phaze it out with Whirlwind.
Skarmory can also run Taunt to stop Umbreon from setting up altogether.
Mienshao
All of the others are OU, so I thought I would post this one incase you're playing tiers.
High Jump Kick.You can run Choice Band or Swords Dance. Choice Band gives you instant power put traps you, although that isn't much of a problem with High Jump Kick. Swords Dance lets you hit even harder, but the problem is wether you can pull one off.
High Jump kick alone is powerful, but for wallbreaking or sweeping abilityyou should run on eof these.
There are more, but to sum it up good checks and counters are Taunt and Hazers/Phazers, along with good wallbreakers with powerful super-effective STAB.
