Heracross @ Leftovers  
IVs: 6 HP / 24 Atk / 24 Def  
- Curse  
- Rest  
- Megahorn  
- Hidden Power [Fighting]  

Exeggutor @ Leftovers  
- Leech Seed  
- Substitute  
- Psychic  
- Protect  

Vaporeon @ Leftovers  
- Acid Armor  
- Growth  
- Rest  
- Surf  

Heracross checks most top threats in GSC 1v1, dealing with Alakazam, Blissey, Exeggutor, Starmie, and Ursaring. Hidden Power Fighting is used for an easier matchup vs Normal- Rock- Dark- and Steel-types, at the cost of a worse Raikou matchup.
Exeggutor is the Electric answer for the team, beating Raikou, Jolteon, Exeggutor, Machamp, and Marowak with Leech Seed, Protect, Substitute, and Psychic. Remember, Protect does not work from behind a Substitute.
If you want more pressure on Water types like Vaporeon, Starmie, and Suicune, Giga Drain and Hidden Power [Grass] are both options over Protect or Substitute.
Vaporeon rounds out the team by covering Fire types and opposing Heracross. It can boost past Blissey, Machamp, Marowak, Ursaring, and many other physical Pokemon that can't get through Vaporeon's Acid Armor.