you need the move strength. go to mt mortars entrance and a guy will pop out and give it to you in hg and ss.
Well any pokemon that can use the strength tm to move that boulder out of the way unless it's a big boulder you cant move that
This boulder is probarly a boulder you need the HM strenght for, which eenables a pokemon to move bulders.
You can move that boulder by using the hidden move strength.
HM04
By using the move strength.
To move a big boulder you need obtain the move Strength. To use the move outside of battle you need the Rainbow badge.
Beat Byron then get strength and then you can use it.
Use Strength. Teach a pokemon Strength (A HM move).
You have to have a Pokemon in your party that knows strength...
If you mean the grey boulder, you need strength and defeat some Gym Leaders so you can use it.
You must have HM04 Strength and the corresponding gym badge to move the boulder.
You have to teach one of your Pokemon the HM 'Strength' and use it.