Payback wasn't introduced until gen 4, and the only stat raising move it can learn is curse which ups its attack and defense while lowering speed, and every Dark type move in gen 3 is a special type attack!!!
Mod note: We no longer allow questions of this style, and ask that any new contributions for Gen 3 movesets be made on the main thread linked below.
You're right, Umbreon wasn't that good in Gen 3. It basically ran Baton Pass sets.
Umbreon (M) @ Leftovers
EVs: 252 HP / 32 Def / 224 SDef
Careful Nature (+SDef, -SAtk)
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