you have to get him from pal park
you can not get regirock in soul silver but in platinum you can in a special event.
You will find Regirock at rock peak ruins route 228.
you cant. you have to migrate them from Pokemon emerald
First Of all it's REGIROCK. Sadly,You can't find on ein Platinum version,either use Action Replay or migrate.
its only in pokemon platinum
to get regirock in Pokemon platinum, you have to upload it from ruby, Sapphire, or emerald.
they have videos on youyube of how to do it
You go to the snowpoint temple but first you need to have the national pokedex and regirock regice and registell.
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