Chaneling
They are creatures that have the ability to increase their power levels by changing forms. The only known chanelings in DBZ are Frieza, King cold, and Coola. Not much is known about their origin or if they are unisex or not.

Cyborgs (Artificial Humans)
Cyborgs were all the creation of Dr. Gero. They are part robot, part human. Their powers increase by abosrbing that of someone else's. They have human organs. (That explains why #18 and krillin had a child) They aren't born nor do they grow. They are created in a laboratory.

Humans
In DBZ they are considered the weakest race. There are two types of humans Males and females. They are all from the planet earth and require 2 people for reproduction. (1 male and 1 female)

Nameks
They are a peacful race with green skin. Nameks have the ability regenerate their body parts. Nameks have the ability to enlarge themselves to any size and to strech their arms. Due to the fact that there are no men or women, you can consider them a unisex race, so only one person is required for child birth. The kids are born from eggs and hatch minutes after their birth. The average power level 1,000-2,000.

Saiyans
The saiyans are a ruthless race that get stronger after they recover from battle. They send babies to weaker planets and adults to stronger planets in order to take over the planet and sell it for a profit. A key characteristic of a saiyan is their tale. When they are exposed to full moon light, it causes them to transform into giant apes.They lived on the planet Vegeta until it was desroyed by frieza. The remaining saiyans were Goku, Vegeta, Radditz, Nappa.The average power level for a saiyan is about 3,000-4,000.