Physical focused, Attack being the highest and decent Special Defense bulk. However its Special Attack isn't great so I think you're going to need to give up on a Fairy STAB.
Since Nature's Madness removes 50% of the target's current HP I'm going to consider it a utility, a move for when Koko doesn't have something else that can seriously hurt its opponent (I wouldn't be surprised if many sets exclude it). But it has its choice of Grass STABs: Wood Hammer or Horn Leech. Other attacks are Superpower/Brick Break, Zen Headbutt, Megahorn, Return, Smart Strike (Steel-type Aerial Ace), Brutal Swing/Payback, and Stone Edge/Rock Slide. For utilities it got Grassy Terrain, Mean Look, Leech Seed, Taunt, dual screens, and Swords Dance.
Bulu may not have a Fairy STAB, but it makes up for it in coverage (sure it can't hit Dragon-types super effectively, but they can't hit it with their Dragon STAB so its all fair).