You can't find registeel in Pokemon HeartGold.
You can't find Registeel in Pokemon Platnium. You just migrate it in Pokemon Ruby, Pokemon Sapphire, and Pokemon Emerald.
...You CAN'T!
by the mountain
cheek seribrii.net
you find it at map 5 or at that place with electric Pokemon
No. You can trade the event Regigigas to HG/SS, and get them, but not in D/P.
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.
u cant
you cant. you can only get registeel from Pokemon sapphire, emerald, and ruby.
Registeel,Regice,and Regirock are all Pokemon your required to migrate from their respective game(s).
you can find them in diglett's cave in kanto