You will need Several HMs: Strength, Surf, Defog, and I believe you will also need rock smash. Go through the Celastic Town entrance, so you don't need to use strength twice. Go up, and use strength on the boulder above. Go down the hall and turn left. Now if you see two grunts, you are not far enough in the storyline. Go down the stairway. Use Defog, and if you want the pokeball, use rock smash. Go up and use surf. Now follow the stairwell, and you should be outside. The first trainer you encounter will have a Aimbom and a Porygon.
Regigigas
First, you will need Surf, Rock Smash, and Rock Climb (and Waterfall if you want to climb the waterfall). Enter Mt. Coronet from the Hearthome City or Oreburgh City side. Make your way northward through the cave. You will have to go outside in the snow at one point. Keep rock climbing till you find a cave that leads back into the mountain, and the next room should have the waterfall.
follow the game.you have to get through mt.coronet.get a ice type,cause it'll hail to your way there. by:poke-expert rookie pearl
You've gotta migrate it through Pal Park from Fire Red & Leaf Green, Which is to detailed and impossible at this point in time to go through. (Nintendo event)
Go to Route 217 outside of Snow point City. (You have to go through MT Coronet to do so) And there is a mean behind a house and he will give you the HM: Rock Climb. He also gives you an icicle shard I think.
area near snow point city and snowy area from mt. coronet
The Item Finder is a Pokétch application that'll be given to you by your Rival as you progress through the story and eventually have to go through Mt. Coronet at some point, it's an automatic scene so you can't miss it, it'll be called the Dowsing Application.
after beating the 6 leagues cross the mt. coronet
go through the north part of Mt. Cornet. Go north thn east till you get to Snow Point.
Regigigas
Your rival will have it at som point
First, you will need Surf, Rock Smash, and Rock Climb (and Waterfall if you want to climb the waterfall). Enter Mt. Coronet from the Hearthome City or Oreburgh City side. Make your way northward through the cave. You will have to go outside in the snow at one point. Keep rock climbing till you find a cave that leads back into the mountain, and the next room should have the waterfall.
snow point gym
the northern part of mt. coronet at all times (the part nearest snow point)
On the way to snow point city.
You have to get there by flying to Eterna City and going through Mt. Coronet.
beat the elite four!