Mosslax is based on the Pokémon species Snorlax.
Mosslax is a special Pokopia character described as a Snorlax that slept for so long that moss and other plants grew over its body. The design turns Snorlax’s famous sleepiness into a visible part of the character’s history and makes Mosslax look as though it has become part of the landscape it occupies.
Snorlax is a Normal-type Pokémon first introduced in Generation I. Its established characteristics include heavy sleeping, a large body, and an ability to block routes in the original Pokémon games. Pokopia reuses those familiar traits but places them in a life-simulation world where environmental change and habitat restoration are central to the story.
Munchlax is Snorlax’s baby Pokémon and is therefore an easy name to confuse with Mosslax. Tangrowth is linked to vegetation but is the species behind Professor Tangrowth, not Mosslax. The “moss” part of Mosslax describes its special appearance and history; it does not change the underlying Pokémon species to a Grass-type.