Armaldo (M) @ Leftovers
Trait: Battle Armor
EVs: 196 HP / 60 Atk / 252 SDef
Adamant Nature (+Atk, -SAtk)
- Rock Slide / Rest
- X-Scissor / Rest
If you can pull it off, this set works amazingly.
Running 252 HP / 4 Atk / 252 SDef also works well.
First you use Block, this will trap your opponent. The goal is to trap a pokemon who can't do anything but set up on you, or who has a general offensive disadvantage when attacking you. The first situation is probably more likely.
Next, now that you've trapped a helpless opponent, you can set up Curse.
It's important to choose an opponent that you can take enough hits from to be able to safely rest off that damage. Next you have your choice of STAB, and Rest to heal off damage. +6 X-Scissor / Rock Slide is normally going to hurt.