Head to the top of the Lost Tower (on Route 209, between Hearthome and Solaceon). Be aware that, although you can reach the top of the tower without Defog, you will not be gifted Strength unless you have used Defog (found in the Great Marsh). If you have used Defog, speak to the two ladies. One will give you Strength and one will give you Spell Tag.
Veilstone.
one of you Pokemon in your party need to learn strength.
You can find the HM strength at the top of the lost tower south of solaceon town :)
The mine badge.
In Pokemon Diamond, Pearl, and Platinum, the HM Strength is given to you by the elderly lady in the haunted tower south of Solaceon Town. She is at the top floor.
none you have to teach it to a fighting type
lost tower :D
Veilstone Gym.
HM 4
Go to the lost tower
Veilstone.
one of you Pokemon in your party need to learn strength.
in the cave with big boulder
Beat Byron then get strength and then you can use it.
Yes it can learn strength
Tower on route 209.
The HM strength