To get Registeel you would have gotten the level 100 Regegigas from a wirerless event or migrate it from saphire, ruby, or emerald.
i think once you have beaten the elite four you can find him in a cave on iron island
If you have the Regigigas from the Toys'R'Us, you can take it to Iron Island to have it unlock a secret room in where Registeel will be awakened. It is level 30 as well.
To get Registeel on Pokemon Platinum, you have to have received a Level 100 Regigigas from a giveaway event. Put it in your party, then you go to Iron island B3F.
If You Have The 12th Movie Regigigas In Your Party,Registeel Can Be Found At Iron Island.
You can't find registeel in Pokemon HeartGold.
beat elite 4
If you have Regice, Regirock, and Registeel.
You can get Regiice in Mt.Coronet. I think Regirock Is In the desert between the resort area and survival area. And Registeel Is at Iron Island. Oh and also you can get it from Pokemon Emerald Version. Hope This Helps
regeggias in snowpoint temple with regirock regiice and registeel on platinum only
you have to have them traded from ruby Sapphire or emerald
you must have regirock, registeel, regiice
You can't. You can get it only through migrating, trading or cheating.