Instructions
Obtain the Lax Incense (or Lax Tag) from the Lost Cave near Chrono Island. The incense grants the player more breeding options, leading to a greater number of rare offspring.
Obtain a male and female Snorlax.
Give the female Snorlax the Lax Incense and place both Snorlax Pokemon in the daycare on Six Island.
Your Snorlax parents will breed and produce and Munchlax, who will be added to your Pokedex automatically.