Munchlax in Ultra Moon?

Question

I had a Munchlax encounter in Ultra moon! I think it shouldn’t be even possible. What happened?

Answer 1

This is normal. Munchlax has a 10% encounter chance on some parts of Route 1.
source

Answer 2

You cannot encounter one in USUM so that must be like a glitch or something. You can trade one from SM though.

Comments

How do you know they can't be found in USM?