1. Unlock Sky Blue Plains.
2. Go to the bullitein board and find a help request from Smeargle and do it.
3. You gain access to Howling Forest. It has 15 floors. Some of the Pokemon you can find there are: Poochyena, Mightyena, Houndour, Houndoom, Shuckle, Spoink, Grumpig, Whismur, Loudred, Snorlax
4. Find Smeargle on the 15th floor and return with him to the base.
5. As a reward, he will join your rescue team! I think he is level 5 and his friend area is obviously Sky Blue Plains. Hope this helped, and happy rescueing!