Wooloo is a sheep-like Pokémon with a thick coat of white wool that makes it look spherical. Its small, black head pokes out of the front of the wool, along with two short horns. Its eyes have yellow sclerae, black irises, and white, horizontal pupils. Two large ears are visible behind gray strings of wool that resemble braided pigtails. Its hoofed legs are short and mostly hidden by the wool, along a with a tail that is barely visible on its rear end.
Wooloo have an extremely fluffy body which can serve as a cushion and help it survive even when falling off a cliff, and stand up without injures. The fur grows back quickly in three months even when shaved. The fur is very popular in Galar, being used for clothing, carpets, very strong cloth, and specialty product. If the fur grows too long, it will be unable to move. Wooloo live in herds mimicking the leader or trainer. They can escape from enemies by simply rolling away due to disliking conflict. Yamper is used to herd the Wooloo.
A Wooloo appeared in Letter, under the ownership of Hop. It was seen playing with its Trainer. Wooloo reappeared in Training, where it was seen watching TV with its Trainer. It then appeared prominently in Buddy, where it became jealous of Hop's admiration of Leon's Charizard and ran away from home. It eventually jumped off a cliff to try and fly like Charizard, only to fail. Wooloo was subsequently found by Milo, who sent Wooloo home on the Flying Taxi. It reunited with Hop, who promised it that they will both challenge the Pokémon League together, and assured that it was perfect the way it was.
Multiple other Wooloo appeared in Buddy, under the ownership of Milo. They alerted Milo to the presence of Hop's Wooloo when it fell into their farm.