Okay, I've been patiently slathering honey all over the shop; have gotten multiple everything elses but have yet to pop a Munchlax.
Now, after having seen my rival's Munchlax, I can check the location on the pokédex...
Area unknown.
So what's the story? Is it a post-E4, or some sort of swarm, or what? I know I'll be able to breed one once I can import, but it seems kinda odd that all the indexes insist that it's a rare tree event.