How do you move rocks in Pokemon Diamond?

Ok, i think you have to steal your friend's secret base flag to move them. I'm not 100% sure but good luck!

-Tim get the HM STRENGTH in the lost tower and teach it to a pokemon.you don't have to steal anything.and i am 100% sure

-------------------------------------------- To move rocks in secret base, steal your friend's base flag. For in-game rocks HM ROCK SMASH or HM STRENGTH should work. Rock Smash is a half-crumbled rock while Strength is a boulder. the second guy is right