They're very rare if you can't yet use Rock Smash, but you might want to get a Geodude from Dewford's Granite Cave. The next Gym will be Electric-type, so a Ground-type that's also resistant to Normal should be a big help.
Combusken and Geodude are both weak against Ground and Water, though, so you should get a pokémon that can handle both...you can get the Old Rod in Dewford, so you can catch a Magikarp and raise it so that it evolves into Gyarados. Geodude and Gyarados cover most of each other's weaknesses, and Gyarados can learn all three water HMs (very bad idea for tournament battle, but helpful for getting through the game.)