Asked in Pokemon Diamond Pearl and Platinum
Where on Pokemon diamond can you find munchlax?
On any honey tree. There's a 1% chance of finding it.
[Other answer]: The best chance is to buy lots of honey and put it on every tree, the best tree to get Munchlax is on the one next to the door at the Valley Wind works just east of that flower place. To get a Heracross smear honey on the tree just west of Eterna City... You will obviously have to wait a whole six (6) hours and fifteen (15) minutes before you get a rare or not so rare Pokemon on a tree so I recommend putting it on just before you go to sleep or before you go to school. Then it's exciting when you get home seeing every tree in Sinnoh shake! Hehe, it gets my hopes up!
Good luck and I hope you get all kinds of rare Pokemon.
ELITE FOUR AND CYNTHIA ARE EASY WITH AN EMPOLEON.... < good luck.