Geodude evolves into Graveler at level 25 ... and getting one on to your team is a good goal to keep in mind. Machop can be obtained from Rock Tunnel, and much later on, Victory Road.
Choosing Cliff, on the other hand, gives you a Shadow Machop and Kanto Marowak at the same stages. Azumarill (Marill's evolution), Steelix, Shadow Machamp (Shadow Machop's evolution), and Kanto ...