that doesnt make sense
you need REGIROCK, REGICE, AND REGISTEEL.
Sorry dude, you can't get registeel in platinum without a cheat. But you can catch Regigigas in Platinum, but you'll need all three of the Regis to get him.
You can only catch Registeel in Platinum if you have the Japanese movie or Toys 'R' Us event Regigigas. Registeel is hidden inside a secret cave within Iron Island if you have the proper Regigigas to unlock it. The cave is near the exit. If you don't have the specific Regigigas then you have to migrate Registeel from Ruby/Sapphire/Emerald.
You need a event Toys R Us Regigigas.
No; you cannot catch the three Regis in Platinum, UNLESS you have obtained a special Regigigas through some special events.
Yes, that is the only way.
You can't because regigigas is a 4th gen pokemon. If you want a regigigas then you will have to migrate Regice, registeel and regirock to Diamond, Platinum or pearl
You need Rigice, Registeel, and Regirock in your party, then talk to Regigigas.
If You Have The 12th Movie Regigigas In Your Party,Registeel Can Be Found At Iron Island.
If you have the event Regigigas, then you go to Iron Island and you will find the Iron Ruins inside. Then, catch Registeel. He should be lvl. 30.
You can only get regigigas only after beating the elite 4 and getting the national dex. It will be in snowpoint temple and you have to have registeel,regirock and regice in your party.
you must have regirock, registeel, regiice