You need to transfer the 3 Regis from Ruby, Sapphire and Emerald and take them to the Snowpoint Temple, Regigigas will wake.
you'd need a rebattle reggigias cheat from action replay if you have one.
Sorry friend, but Pokeflutes are for Snorlaxes.
in the temple in snow point
The first step is to have Regirock, Registeel, and Regice in your party. You have to migrate from Emerald, Saphire, or Ruby Red. Second, you have to defeat Candice (seventh gym leader in platinum) to get into the tower (far north of Snowpoint City). Third, you have to get to F5 (floor five going down) in the tower. Fourth, you will see a statue of Regigigus. Fifth, (this is where the regis come in) you must have the regis in your party or it will not work. The regis bring Regigigus back to life and you get the oppertunity to catch it and battle it. P.S. Regigigus is very weak so use Level 3s and 4s to catch it. Regigigus is level 1.
in the ice temple in snowpoint sity
No, you can not find regigigas in Pokemon Heartgld without using an Action Replay.
there isn't one
no you can't find a Regigigas in Pokemon Heartgold at all. That person used cheat codes to make a Regigigas appear out of nowhere.
if you want a registeel you can have my one i used to get regigigus. Lv. 30. see ya on WI-FI!
A quick ball would be helpful for the first few turns if we're talking platinum.
you cant you have to trade it and if you want to catch the other regis you have to regigigus in your party and then for regice go to end of mt coronet for registeel you go to cave of origin and take your mothers exit find the rest of the way yourself and for regirock you go to route 229 thats all i know
There is no rental Pokemon in in Pokemon platinum