You need to smash the boulder in the cave link between verdanturf town & rustboro city. when you smash the rock the man will thank you because he can see his girlfriend everyday and you get HM04 (strengh)
Walk to Vendaturf Town and enter the cave in the west. Some guy will give you HM04.
HM04 is the strenght move
HM04 In Heart Gold and Soul Silver is Rock Smash.
Pushing boulders is a feature that can only be done with HM04 Strength. HM04 is received after you find the Safari Warden's Gold Teeth in the Safari Zone. When you have the Gold Teeth, give it to the Safari Warden and he will reward you with HM04.
HM04 Strength, can be found in Nimbasa City, specifically from a man in the building northwest of the Pokémon Center
lost tower
Use HM04- Strength
You use an HM04 move called Strength. The HM04 strenght is found on Iron Island. Go to canalave city and get on the boat to Iron Island. When you get to the island there is a lady blocking a cave. Talk to her and she will give you the HM04 move Strength.
You get it from the safari warden
You Just Get The gold teeath in the safari zone and give them to a man in a house in fuchsia city and then you get hm04 P,S its a old man that is alone in a house.
From HM04, it will be one of the HMs you get during the game.
Strength is HM04. You teach it.