I hated how late this guy appeared in Gen V games, but loved the concept.
Stats:
-HP - Good-bordering-Great - Base 95 is really solid for a Normal Type.
-Attack - Great - Base 110 is also solid.
-Defense - Good-bordering-Great - Base 95 is great for sponging hits with Base 95 HP.
-Sp.Atk - Bad - Nothing to see here. Move along.
-Sp.Def - Good-bordering-Great - Base 95 is great for sponging...whoa...deja vu...
-Speed - Dead Zone-bordering-Good (Trick Room) - Base 55 is a little fast for my Trick Room preferences, but too slow for you not to consider Trick Room. At least you can tank hits well...
Abilities:
-Reckless - Great for Head Charge and Wild Charge, but nothing else.
-Sap Sipper - One good predict and you can get an Attack buff, but only against opponents that actually use Grass-Type Moves.
-Soundproof (Hidden, Available [Poké Transfer]) - Could be worse, but blocks some nasty Moves like Roar, Bug Buzz, Boomburst, Perish Song, and Grasswhistle, for examples.
Overall, Bouffalant is a lot like an actual tank: Bulky, hard-hitting, and slow. It's a great Normal Type, but its Movepool doesn't reflect that too well. What it does get, however, is quite effective. Compared to other Physical-oriented Normal Types, it's a welcome addition from Gen V. Tauros has Speed, Miltank has Physical bulk, and Snorlax has Special bulk, for examples, but Bouffalant brings a well-roundedness that they lack.
However, well-roundedness also means drawbacks. Sp.Atk takes a huge hit, but it's just a negligible one when you have a Physical Attacker. Speed, however, suffers likewise. Many things outrun Bouffalant both inside and outside of Trick Room. Plus, it has no way of blocking Status Effects unless they are Grass-Typed or Sound-based, and, even then, it's either/or if you aren't running a Reckless Ability-Head Charge/Wild Charge set.