The only way to obtain a Heatran in Pokemon Heart Gold/Soul Silver is to trade it.
Chat with our AI personalities
You can't. You need to get Heatran from Pokemon Diamond, Pearl and Platinum and then trade to heartgold and soulsilver.
You need Ho-oh and Lugia
No. Heatran is unobtainable (and therefore does not exist) in PoKéMoN HeartGold & SoulSilver, so you'll need to trade it from PoKéMoN Diamond, Pearl or Platinum (you can find him in the deepest part of Stark Mountain).
Heatran is unobtainable (and therefore does not exist) in PoKéMoN HeartGold & SoulSilver, so you'll need to trade it from PoKéMoN Diamond, Pearl or Platinum.
You find Heatran in the third room at the end of Stark Mountain, which is available after you beat the Elite Four.