It protects itself from the cold by wrapping up in leaves. It stays on the move, eating leaves in forests.
– Pokemon White Pokedex
Swadloon’s expression is awesome. I love its “I’m not amused” face. Like the Bug/Grass types of previous gens, the middle stage is a cocoon.
It evolves into Leavanny not by level up, but by happiness. I guess it’s probably not very happy to be stuck wrapped in its leaves like that, and will only evolve when you make it happy, haha.
In the anime, Ash’s Sewaddle just recently evolved into Swadloon. Except, it somehow evolved in the middle of the battle against a gym leader, after it was hit with Solar Beam… yeah. The anime does not follow game rules.