Can anyone recommend some teammates for my Fire/Water/Grass core?

Starmie @ Life Orb
Ability: Analytic
EVs: 252 Spd / 252 SAtk / 4 SDef
Timid Nature
- Rapid Spin
- Hydro Pump
- Ice Beam
- Rapid Spin

Heatran (M) @ Air Balloon
Ability: Flash Fire
EVs: 252 Spd / 252 SAtk / 4 SDef
Timid Nature
- Fire Blast
- Earth Power
- Stealth Rock
- Hidden Power [Ice]

Tangrowth (M) @ Assault Vest
Ability: Regenerator
EVs: 252 HP / 72 Atk / 184 SDef
Sassy Nature
- Giga Drain
- Knock Off
- Earthquake
- Hidden Power [Fire]