When attacked, it escapes by shooting cotton from its body. The cotton serves as a decoy to distract the attacker.
They go wherever the wind takes them. On rainy days, their bodies are heavier, so they take shelter beneath big trees.
Perhaps because they feel more at ease in a group, they stick to others they find. They end up looking like a cloud.
When it finds others of its kind, they all stick together. When enough of them have collected, the mass resembles a cumulonimbus cloud.
Pillows and beds stuffed with cotton exhaled by Cottonee are soft and puffy, light and airy— altogether top quality.
— Pokédex entries (via PokeAPI)