How do you get HM4 strength in Pokemon pearl?

It Is Located On The 5th Floor Of The Lost Tower. The First Old Lady Will Give It To You. (If You Are Wondering Where The Lost Tower Is, It Is In Solaceon... The Town Where The Day-Care Lady Is) :D Happy Gaming!
It is in the Lost Tower, at the end of the north end of route 209, just below Solaceon City. You have to make your way to the very top of the tower, battling several trainers. After beating some old woman, she will give you HM04 (strength).