get the mind badge at the canalave gym in canalave city
use strength
You can use any Pokemon that is able to learn Strength to push rocks.
you can get it in pokemon platinum!
Use the hm strength.
if you have a pokemon with strength use the move to push the stone into pit
strength
his or her level and exp.
By using the move strength.
Maylene is located at Veilstone in Pokemon Platinum. Maylene is a gym leader and is unaware of the amount of strength she possesses.
lost tower 5th floor
In the Unown Cave, east of Soleacon Town.
you need to have a Pokemon with the hm move strength touch the boulder and it will say if u wanna use strength say yes and there u go! hope i helped