Which Gym Leader allows you to use strength?
Using Strength Outside of Battle
In the field, Strength is used to push heavy boulders out of the way. It requires the Mine Badge to use in this manner, so you will need to defeat Canalave City's Gym Leader first.
Byron then go to iron island and riley gives you it
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.
the fourth gym its a fire gym
a gym leader can't teach a Pokemon that move but you have to defeat the 6 gym leader in order to teach that move
beat a gym leader
in pearl, diamond, and platinum the 6th gym
In Pokemon Red/Blue/Yellow and Pokemon FireRed/LeafGreen, the Celadon City Gym Badge is required to use Strength. Gym Leader Erika holds this badge.In Pokemon Gold/Silver/Crystal and Pokemon HeartGold/SoulSilver, the Goldenrod City Gym Badge is required to use Strength. Gym Leader Whitney holds this badge.In Pokemon Ruby/Sapphire/Emerald, the Lavaridge Town Gym Badge is required to use Strength. Gym Leader Flannery holds this badge.In Pokemon Diamond/Pearl/Platinum, the Canalave City Gym Badge is required to use Strength. Gym Leader Byron holds this badge.In Pokemon Black/White and Pokemon Black 2/White 2, Gym Badges are not required to use HMs.
You get stregth after you beat the canalave city gym leader
By defeating the the fourth gym leader
It's the gym leader that allows you to use strength after you beat him.
In canalave city
If you were paying ANY attention to the gym leader in Canalave city, you should know its Canalave city.
you have to get the hm strength then beat the gym leader in canalave city