The cotton-candy monsters were the disguises of a science genius kid and his two friends.
Scooby-Doo! (DC Comics)
The kid wanted to ruin Mr. Tonklin's carnival in revenge for being fired. He thought his genius with chemicals could have improved the snacks, but Tonklin said even a genius couldn't improve the hot dog. He and his friends wore scuba suits and covered themselves in cotton candy to disguise themselves. (Goop On The Loose)