sumwun is correct.
A Pokemon's current state of evolution does not affect the stats of its offspring. However, you will not be able to breed certain Pokemon unless they are or are not evolved:
For example, Nidoran female can breed with anything in the Field, Monster, or Ditto egg-group but its evolutions cannot. Baby Pokemon, including Pichu, Cleffa, Igglybuff, Togepi, Tyrogue, Smoochum, Elekid, Magby, Azurill, Wynaut, Budew, Chingling, Bonsly, Mime Jr., Happiny, Munchlax, Riolu, and Mantyke all cannot breed until they evolve.
The stats of a Pokemon are affected by Individual Values (IVs), Effort Values (EVs), and Natures. When breeding, the offspring will inherit 3 IVs for different stats from a random parent, and the other three IVs will be chosen randomly. You can breed for specific stats using certain parents and items.
Since I'm not sure what game you are playing, I will offer the link for a general guide on breeding as a whole rather than a guide for a specific generation. I suggest you read through Bulbapedia's page on breeding here.
Knowledge is priceless, my friend.
