Munchlax, much like Wynaut, is a bit of a tricky Pokémon to breed in Pokémon Brilliant Diamond and Shining Pearl. Attempting to breed two Snorlaxes (or one Snorlax and one Ditto) together will normally yield another Snorlax. However, one item that can be found in Veilstone City will allow the Sleeping Pokémon to produce Munchlax eggs.
This item is the Full Incense, and you can find it on top of a small rock mountain right next to the city’s Pokémon gym. To get to it, you’ll need to have unlocked the Rock Climb ability, which isn’t usable outside of battle until after you beat the seventh Gym Leader, Candice. Climb up the small slope and the Full Incense will be yours.
Now, make sure you have either two Snorlaxes of the opposite gender, or one Snorlax (doesn’t matter which gender) and one Ditto. Ditto can only be caught after unlocking the National Pokédex, while you can only acquire a Snorlax by evolving a Munchlax, which can either be caught via Honey Trees or by exploring the Grand Underground. Equip your Snorlax with the Full Incense and place it in the Pokémon Nursery with its partner. Eventually, a Munchlax egg will be produced. You can use the Pokétch’s Egg Monitor app to check whether an egg has been produced or not.
