in pearl, diamond, and platinum the 6th gym
It's the gym leader that allows you to use strength after you beat him.
You have to beat the gym leader in Canalave City. you get the hm in the lost tower on the way to Soclan town.
i am pretty sure it's strength.
beat the forth gym leader
You have to beat Erika, who is the fourth Gym Leader, raises Grass-Type Pokemon, and resides in Celadon City.
I believe that is after you've beaten the 4th Gym in Volcanoridge Town.
byrons gym at canalave city. You have to use surf at route 218(west of Jubilife City) and then you can get in canalave city.
The Gym Leader that allows you to use the HM move Strength in Pokemon FireRed is Erika. Erika is the Gym Leader of Celadon City and is the 4th Gym Leader the player faces.
In Emerald you have to beat Flannery in Lavaridge But to get Strength you have to smash the rocks in the tunnel between Rustboro and Verdanturf. Good Luck!
on diamond u should go to eterna and go use strength on the boulder! then go north to face the snowpoint gym
After you beat the sixth gym leader, you are allowed to use strength which moves the boulders.
I think you must beat Erika the fourth gym leader in Celadon City