ok i found it at the walkthrough (this is a copy of it)
Breeding is an essential thing to raising good Pokemon. There are many
advantages to it, such as passing new moves and TMs or getting multiples of
rare one of a kind Pokemon. Breeding is easy, all you have to do it beat the
Elite 4 and get to Island 4. There will be a breeding center there. Get a male
Pokemon and a female Pokemon in the same egg group and let them sit there.
Come back later and you may find an egg. Hatch it into a Level 5 Pokemon.