I wrote this on Smogon :^)
I've recently started using a physically defensive Bouffalant with great success:
Bouffalant @ Life Orb
Ability: Reckless
Shiny: Yes
EVs: 4 HP / 252 Atk / 252 Def
Adamant Nature
- Head Charge
- Earthquake
- Megahorn
- Stone Edge
I never see anyone talk about Bouffalant, even in the lower tiers, and after using this set, I honestly have no idea why. While its most powerful attack is less efficient in a metagame where ghosts are quite common, it doesn't stop it from having a huge offensive presence, thanks to its unresisted coverage. It also works as a great pivot thanks to its defensive typing and physical bulk.
As an example of all the former statements, you can see that this set can take a LO Sacred Sword from Aegislash:
252+ Atk Life Orb Aegislash-Blade Sacred Sword vs. 4 HP / 252 Def Bouffalant: 255-302 (76.8 - 90.9%)
...and retaliate with a OHKO EQ:
252 Atk Life Orb Bouffalant Earthquake vs. 4 HP / 252 Def Aegislash-Blade: 299-354 (114.1 - 135.1%)
Now, Bouffalant is by no means a perfect Pokemon since it can be stopped by a few common threats, such as Air Balloon Aegislash, and it'll eventually KO itself due to all the residual damage, but the amount of work it can do without team support is simply impressive. I think the perfect way to describe it is: It's kind of like an invisible truck. It hits hard and most people won't see it coming.
I'll leave this replay here, since it does a great job at showcasing Bouffalant's potential, IMO:
http://replay.pokemonshowdown.com/pokebankoubeta-66895549 