i'm in your conscience
Geodude in Granite Cave would be a good idea. :) It resists Electric moves. If you have a Mudkip or Torchic in your PC that you ditched, training them up, especially Mudkip, would be really good as well. Marshstomp is a Ground type and gets Mud Shot upon evolving from Mudkip and Combusken gets Double Kick in similar fashion. Going back for an Aron is also an option, though it only gets Mud-Slap.