My starter was Tsutaaja, which has been very helpful with quite a few gyms (Though it wasn't so helpful in the flying gym and the ice gym). At the start of the game I caught a
Yooterii, which quickly learns Bite, and later Double-Edge and Crunch, which are pretty useful. I also got myself a
Dangoro, which learns Rock Blast quickly, and that's extremely useful. It also has Sturdy, which is now a free Focus Sash, and that's come in useful countless times.