Bronzong @ Leftovers
Ability: Levitate
EVs: 252 HP / 4 Atk / 252 SpD
Sassy Nature
IVs: 0 Spe
- Stealth Rock
- Toxic
- Gyro Ball
- Zen Headbutt
Bronzong can take ground attacks for Heatran and is also neutral to fighting and water, so it's an ideal teammate. Since it has stealth rock, it can free up heatran to be more offensive or for it to have a toxic + protect stalling set. Bronzong is a decent check to Landorus since it can switch into Earth Power and 2hko it.
252 SpA Life Orb Sheer Force Landorus Focus Blast vs. 252 HP / 252+ SpD Bronzong: 133-156 (39.3 - 46.1%) -- guaranteed 3HKO after Leftovers recovery
0 Atk Bronzong Gyro Ball (131 BP) vs. 0 HP / 0 Def Landorus: 141-166 (44.2 - 52%) -- guaranteed 2HKO after Stealth Rock
Last move is filler, screens/eq/other random move like trick room can also be used.