i have this tendency to take pokemon with average defenses and give them defensive EVs just for the heck of it, so without further ado:
BAM!@Leftovers
Chlorophyll/Herbivore
252HP/4Atk/252Spe
Jolly
-Swords Dance/Agility
-Substitute
-Wood Horn
-Baton Pass
Preferably, if his ability is Chlorophyll, use Swords Dance so you'll be faster than everything under the sun (use with Drought or any Sunny Day invoker); if ability is Herbivore, use Agility, but mix and match as you please, any combo could work just as well. As my personal preference, I'll use Swords Dance over Agility any day for this set. Now, to explain the set:
1.) Come in on a resisted attack or something he can force out (like Swampert/Quagsire), throw up a Sub on the switch; alternatively, if he starts out as your new active pokemon to replace a fainted one, still throw up a Sub to protect against status or simply to scout.
2.) Once safely behind a Sub, use Swords Dance, then pass it next turn as your Sub breaks (or DOESN'T break, in which case, it's a bonus).
Why the HP EV's? Why don't you just dump everything into Attack for Wood Horn? Well, my answer to that is that we want to make this deadly deer survive long enough to pass a boost. The extra bulk will also make his Subs a little more durable (though not much). And with Swords Dance boosting your attack anyway, Wood Horn's going to cause some damage (and heal some of yours in the process). Alternatively, he can semi-stall with the combination of Sub and SD-boosted Wood Horn (but not for long--max 16PP for your only offensive attack).
I am liking this thing more and more everytime I theorymon it.