there will be a lady at the start of the path next to the forest near nacrene city if you speak to her she'll give you it
You use the Rock Smash TM
you find it
Find a Pokemon that can learn Rock Smash. Like Geodude.
Strangely, Rock Smash is not a HM. It is a TM. The girl at the entrance of Pinwheel Forest gives it to you.
you can find the legendary Pokemon regirock
In Pinwheel Forest.
1) Find the HM Rock Smash. 2) Tech it to a Pokemon 3) Press A while facing the rock you want to crush.
Rock Smash-ing the Rock Smash-able rocks at the Ruins of Alph
you can find rock smash by talking to a man just to the right of where sudowoodo was (violet city side)
You can't but there is a hack/cheat to do it.
You use rock smash and can sometimes find fossils.
You can find it by chance when you use rock smash on rocks