Pokemon have a starting CP (Combat Point). These determine the combat potential that the Pokemon have.
Raising CP
Leveling Cost
1 - 200 Stardust + Pokemon Candy
2 - 400 Stardust + Pokemon Candy
3 - 600 Stardust + Pokemon Candy
5 - 800 Stardust + Pokemon Candy
6+ - 1000 Stardust + Pokemon Candy