There is no 'Breeding Center' in any of the Pokemon games. However, you can breed two Pokemon in the Daycare, located south of Goldenrod City.
You can only get it from breeding it from Jigglypuff or Wigglytuff
He only learns it via breeding but only in Pokémon HeartGold and Pokémon SoulSilver.
You can get a Munchlax by breeding it with Snorlax holding a Full Incense, or you could transfer it from the Poke Walker.
It is in Viridian City, behind the Poke Center.
You get it from bill in goldenrod city after you find him in the Pokemon center in the next town.thanks