Heart Gold and Soul Silver: Basic Breeding
Breeding was originally introduced in Gold and Silver and has been a staple of Pokemon ever since. The basics of breeding are simple, but it can get very complex quickly. As with any breeding, Pokemon breeding requires one male and one female. The two Pokemon must be of the same Egg Group
in order to make an egg.
In order to get two Pokemon to make an egg together, you must put the two compatible Pokemon in the Daycare Center south of Goldenrod City. If the two Pokemon aren't compatible, the man outside of the Daycare Center will say "The two prefer to play with other Pokemon than each other." In order for the two compatible Pokemon to make an egg, you must walk around. Each step determines whether an egg will be made. You can pick up your egg once you get a call in your PokeGear from the Daycare Center saying your Pokemon have made an egg.
Once you have picked up your egg, hatching it is a matter of steps. When your Pokemon egg is generated, a number of steps needed to hatch it is created. You must walk (or ride your bike) that number of steps while the egg is in your party in order for it to hatch.
Every Pokemon hatched from an egg will be level 1 and the basic from of the female parent.
Please note that this information is meant to be simple and many of the more complex aspects of breeding have purposely been left out.