Kimahri is a versatile character. The fact that he begins in the center of the Sphere Grid is an advantage, because you can choose any direction to further Kimahri's development on the Sphere Grid. It all depends on how you choose to develop Kimahri.

Kimahri has a small area on the Sphere Grid. Soon, the player must choose a path of another character for Kimahri to emulate and unlock it using a Lv. 1 Key Sphere. If you want Kimahri to hit harder, follow Wakka's path. To make Kimahri into a thief, follow Rikku's path. If you want Kimahri to become more agile and learn Haste, follow Tidus' path. Lastly, if you want Kimahri to cast magic, follow Yuna or Lulu's path. Pick a path of your liking and follow it.
Develop Kimahri to suit your own preferences, and you'll probably enjoy using him more in combat.

Except for Jump, Kimahri learns enemy skills by using the Lancet ability. Whenever you encounter new fiends, lancet or scan them to find out if you can learn any new overdrives, whenever you do, the Overdrive gauge will fill.