You can't. for some reason they did make rock smash an HM in gen 5.
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any pokemon but some can break rock if you teach them the hm
You need a Pokemon with the move Rock Smash.
You can break rocks by using the move Rock Smash.
Teach the HM Rock Smash to a Pokemon and interact with the rock. Round rocks need the move strength and not all Pokemon can use these moves.
You can get it in Icirrus City.