Within
Pokemon FireRed, there are seven different HMs (Hidden Machines) to obtain during your journey. HMs work a lot like
TMs in that they are moves that can be taught to your Pokemon; however, unlike TMs, HMs last forever and even can be used in the overworld. Obtaining all of the HMs will also be vital, since you won't be able to complete the entire
Main Story &
Post Game without them.
HM04 is none other than the move known as Strength. HM Strength can be obtained from the
Safari Zone Warden in
Fuchsia City by returning him his
Gold Teeth (found in Area 4 of the Safari Zone). HM Strength will allow you to move boulders blocking paths across the
Kanto Region. You will need this especially when on
Seven Island later in the
Post Game in order to complete the Boulder Puzzle to unlock the
Tanoby Ruins.