by the mountain
You can't find registeel in Pokemon HeartGold.
it's at the place where you can catch electrike, mareep, registeel, zapdos, voltorb.ect. you can also find steel types there PS:Pokemon crater is closed now. But you can go on www.tppcrpg.net
You can't find Registeel in Pokemon Platnium. You just migrate it in Pokemon Ruby, Pokemon Sapphire, and Pokemon Emerald.
...You CAN'T!
cheek seribrii.net
you find it at map 5 or at that place with electric Pokemon
go on Pokemon crater
Pokemonbattlearena.net
in your house
you can rarely find larvitar.
Registeel is a Steel type pokemon.
You can find Registeel in the Ancient Tomb on Pokemon Ruby, Sapphire and Emerald. It can also be found in the Underground Ruins of Pokemon White2. To get Registeel in Pokemon White2 you need to catch or defeat Regirock and use the Iron Key reward to unlock the Iron Chamber containing Registeel.