Here are the places I used:
HP: go to Rusturf tunnel and whack Whismur
Attack: you can for Poochyena in early routes, alternatively, you can fish for Carvanha
Defence: Koffing and Torkoal (+2) in Fiery path
Sp. Attack: Spinda and Slugma on Route 113, alternatively, Slugma and Numel in Fiery Path
Sp. Defence: this one might take some time as you're pretty limited, but I personally used Swablu on Route 114, alternatively go for Tentacool
Speed: Zubat in Altering cave