(Um i don't think you can get in from platinum but i do know you can get in on Sapphire Pokemon game for GBA games. You can get the steps for getting regirock at YouTube but you have to get the game Sapphire too. :))
You actually can get it on Pokemon platinum but first you need the event regigigas from the eleventh movie. then you go to a cave on route 228. once inside, walk on all of the circular pieces on the floor (order doesnt matter) then the ground will shake. after that go up to the statue and press a. it will initiate a battle with regirock. do the same thing in the last room of iron island and the last room of Mt. Coronet when heading toward
snowpoint city to get registeel and regice. but remember, regigigas must be in your party.
its only in pokemon platinum
to get regirock in Pokemon platinum, you have to upload it from ruby, Sapphire, or emerald.
you can not get regirock in soul silver but in platinum you can in a special event.
you have to get him from pal park
they have videos on youyube of how to do it
You will find Regirock at rock peak ruins route 228.
level 30
it is in route 228.
you need REGIROCK, REGICE, AND REGISTEEL.
regeggias in snowpoint temple with regirock regiice and registeel on platinum only
no you do not.hope this helps:)
you cant. you have to migrate them from Pokemon emerald