You're right, Umbreon wasn't that good in Gen 3. It basically ran Baton Pass sets.
Umbreon (M) @ Leftovers

Trait: Synchronize
EVs: 252 HP / 32 Def / 224 SDef
Careful Nature (+SDef, -SAtk)
- Mean Look
- Baton Pass
- Taunt
- Wish / Moonlight
For more sets, visit Smogon.