Well, Sucker Punch does slightly offset that by being a priority move... but I see what you mean.
Thankfully, Umbreon's Defence and Sp Defence (Especially Sp Defence. When you can take Draco Meteor from a pokemon 20 levels higher than you, you know you have huge Sp Defence) are his highest stats. And let us not forget that helpful move named Moonlight. When you add together his defensive skills, ability, access to recovery (Moonlight and Wish) and refreshery (Heal Bell), it really shows how awesome Umbreon is. ^_^
Since my favorite pokemon is umbreon i want to be able to use him when playing through the different games, however, since his attack (and spat) sucks this is rather hard, i would like to see him learn moves like nasty plot and dark pulse or sword dance and some other dark physical move (not faint as it is too weak), preferably with 80+ in dmg...
I also like umbreon. And I happen to know he CAN sweep.
His attack isn't too bad. Tutor him Sucker Punch and he does great. If you want to boost his Attack and pwn, breed him to learn Curse, and TM him Payback. And for your information, there is NO dark attack with +80 in damage. Crunch, Dark Pulse, and Sucker Punch all tie at 80. However, if you go after the opponent while using Payback, it's 50 power doubles to 100. Hence Curse+Payback. And don't forget STAB. Since Umbreon is a dark-type, Sucker Punch raises to 120 power, and Payback (If used after the opponent) raises to a fantastic 150.