Go to the west of the city towards Mt. Mortar. A man will run out he will give you Strength (HM04)
Teach the HM Strength to one of your Pokemon and use Strength on the boulders
Use the HM Strength.
First, you have to get the HM strength, then teach it to and a Pokemon and you can move boulders.
You can't break them. You use strength(hm04)and push them with a Pokemon that knows that move.
You have to have the HM Strength which you can find on Iron Island with Riley.
The move in Pokémon Diamond that allows you to move boulders that are in the way as you're traveling the Sinnoh region is called Strength. Strength is a Hidden Machine that you can find in the top floor of the Lost Tower.
Strength
How do you move boulders in Pokemon:LEAF GREEN - FIRE RED - YELLOWTo move boulders you have to learn a HIDDEN MOVE (HM)called STRENGTH.You get this HIDDEN MOVE (HM) by giving the Warden in Fushia City hisGold Teeth back.You can find his teeth in the Safari Zone, close to the Secret House.The Warden lives at the east-side of Fushia in a house with a pond behind it.
To move boulders in Pokemon Gold you need a Pokemon with the HM move Strength. Selecting the Pokemon in the menu outside of battle should let you use it if you have beaten the Olivine City Gym.
you mest get the hm strength.
Use the HM move Strength.
With the HM move strength.