Caves, Mountains, and some select gyms (Faninita's and Janine's, respectively)
Caves: Spammed with zubats and geodudes, maybe the occasional psyduck/ratatta. So many, so I stick on using repels.
Mountains: same thing, but the water in some, respectively.
Gyms: Their little tricks, getting bombed with trainers -n-
and in yellow, rocket hideout. You spin SOOOO slow, and imagine how your poor little pikapi feels!