Dragonite @ Scope Lens  
IVs: 14 HP / 24 Atk / 26 Def  
- Hidden Power [Flying]  
- Surf  
- Thunderbolt  
- Ice Beam  

Heracross @ Leftovers  
IVs: 6 HP / 24 Atk / 24 Def  
- Counter  
- Curse  
- Megahorn  
- Earthquake

Blissey (F) @ Leftovers   
- Counter  
- Curse  
- Rest  
- Double-Edge  

Dragonite handles most Ground, Grass, and Steel types. Scope Lens lets it crit through Vaporeon.
Heracross guarantees most Electrics, along with beating Psychics, Normals (though HP Flying Tauros is shaky), and Tyranitar.
Blissey handles the remaining threats for the team like Gyarados, Articuno, and special attackers lacking Growth or Encore.