By using the HM Strength you can move boulder's
First, you have to get the HM strength, then teach it to and a Pokemon and you can move boulders.
HM "Strength" is used to move boulders.
You might move boulders off of the seafloor cavern into a ship in order to examine the boulders. Often, this is accomplished using buoys that float the boulders from the seafloor to the ship.
To move the boulders and clear a path. If there are two types of boulders in your version the boulders with cracks need to have rock smash used on them instead of strenght.
Strength
you get the HM strength
you mest get the hm strength.
Use the HM move Strength.
With the HM move 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 get past the boulders you have to let one of your Pokemon to learn the move strength.
just push all the boulders