If you have Pokemon Diamond or Pokemon Pearl, then HM Strength will be in the Lost Tower outside of Solaceon Town. If you have Pokemon Platinum, it will be in Iron Island, which you can only access once you have reached Canalave City.
Go to Fuchisia city and then go to the safari zone. Once you get to the end of the safari zone you will see a pokeball with the gold teeth in it. Grab it and when you are done in the safari zone go to the warden's house which is also in Fuchisia city and he will trade you the teeth for strength.
There are 2 old ladies in the lost tower on the top floor. One of the old people will give it to you. That's how you find it so old ladies aren't useless.
You have to go on one island then go in ember spa you will see an old man now talk to him he will give you HM.
This boulder is probarly a boulder you need the HM strenght for, which eenables a pokemon to move bulders.
Hm 01-cut hm 02-fly hm 03-surf hm 04-strength hm 05-flash hm 06-rock smash hm 07-waterfall hm 08-dive
There are 8 HM's: Hm 01: Cut Hm 02: Fly Hm 03: Surf Hm 04: Strength Hm 05: Defog Hm 06: Rock Smash Hm 07: Waterfall Hm 08: Rock Climb
you get the HM surf at the lost tower on Route 119 go to the very top of the lost tower at route 119 and there will be two old ladys one gives u strength and the other a clense tag.
There are 9 HMs HM:01 Cut HM:02 Fly HM:03 Surf HM:04 Strength HM:05 Flash HM:06 Whirlpool HM:07 Waterfall HM:08 Rock Smash HM:09 Rock Climb
With hm strenght.
you can get it in the tennel under mt. chimney but you will need hm rock smash and hm strenght
Strenght is an HM move, teach it to one of your'e pokemon. to use it just select your'e pokemon and select strenght.
35.........but Trampinch must know the HM strenght in order to evolve
Fly, Surf, Strenght, Waterfall, Cut, Dive.
Go to Iron Island and talk to Riley, he'll give it to you.
in Nimbasa city the building on the top left talk to the lady on the left
You must have the following HM: Strenght and Rock Smash.
you need hm strenght you can get it at fuchsia city safari zone
Bibarel he can learn waterfall, strenght, surf, rock smash, rock climb,
To use strenght outside battle you need: A Pokemon that knows strenght or the HM so you can teach it to a Pokemon The Mine Badge from Byron in Canalave City. Have a Pokemon knowing strenght on your team and go to a place where you need strenght. Press A in front of the big, grey boulder you want to move and use strenght. Now when you walk, you'll push the boulder in front of you. You don't have to use strenght for every new boulder, you'll only have to re-use it if you go in another room.
in lost tower . it is on route 209. when you see the 2 ladies at the top talk to them. i /think/ you might have to battle them. i doubt it though.