This mossy rock is found in Eterna Forest. Since Leafeon hail from the Sinnoh Region, you can find many living here.
There's also a mossy rock in the Unova Region. Many people come there who live close, but everyone who lives far away from Pinwheel Forest just uses mossy trees or even their mossy food! .....Gross.
It's unknown where moss can be found in the star-shaped undiscovered Kalos Region, but still, anyone can grow their own moss..... ....what?