beat the elite four, then the girl blocking the way will let you in. just go up from snowpoint city.
beat snowpoint gym
a skier in snowpoint mountain has one
become champion or have all three regis, you can only get regigigas if you have all three regis
Rock Climb is on your way to Snowpoint City.
You catch Regigigas by migrating Regirock, Regice, and Registeel from a GBA game then go to the Snowpoint temple in Snowpoint city.
You have to have caught Reggierock,Reggieice,and Reggiesteel, and have them in your party, to enter.(You get these Pokemon from GBA games with pal park.)
It is somewhere in the Battle Frontier and to get there you need to win the Pokemon league and go to snowpoint city and talk to the sailor
In Snowpoint Temple. You need the 3 Regis to awaken him. Bring a low leveled pokemon, as he is only Lv1. I'm serious.
You have to get regi rock regi steel regi rock then go to the tempo in snowpoint only(soul silver ,heart gold,dimond ,pearl,and platnium)
You don't need rock climb to get to Snowpoint city. You just take a right when you see the lake.
Before you go to Snowpoint City, there is a house with hiker in it. Not so far from it, there is an item. Pick it up, and it's HM Rock Climb.
9P/Tempel or Tempel 1 is a comet, not an asteroid.