Some early things you might want to consider:
- Kricketune. Kricketune is known as the best early game Pokemon, because with Technician + STAB Fury Cutter, it's a wrecking ball. Fury Cutter boosts its power every time you use it consecutively, if you didn't know.
- Whismur. Whismur is a weaker version of Kricketune, as it does not have Technician, but STAB Echoed Voice is still an amazing thing to have. You don't even need to worry about Ghost types if you have Scrappy. Unfortunately, you might miss out on your chance of finding Whismur if you fight Julia before catching it.
- Mightyena. Mightyena + Moxie + Bite = rip first few Gyms
- Bunnelby. You can find one before the third Gym, and it's amazing with Huge Power.
etc.