Good early Pokemon that come to mind are Azurill (if you didn't pick Oshawott), Lillipup, Magnemite, Scraggy, Drilbur, Darumaka, some of the better Eeveelutions, Sandile, Sigilyph, and if you were playing White 2, the stationary Braviary in Route 4 (Black 2 gets Mandibuzz instead, which is still great).