Are you looking to sweep or revenge with it?
There are a few different ways to make mence work. My personal favorite is as a setup sweeper using something like this.
Salamence @ Flyinium Z
Ability: Moxie
EVs: 252 Atk / 4 Def / 252 Spe
Jolly Nature
- Dragon Dance
- Fly
- Dragon Claw/Outrage
- Earthquake
There are a few ways to fit this set to your team's needs, but the basic idea is that you can use mence's decent speed tier and access to dragon dance to abuse moxie. Z-fly helps you pick up your first KO and you can very easily work from there.