"The 'Pink Avengers', an elite corps of flying pigs who swoop down from the clouds whenever their hotline alerts them to someone who is crushing the dreams of a pig. " ―Pig.
The purpose of the Pink Avengers is to protect innocent and dumb pigs, such as Pig, from people like Rat who would try to crush their dreams.
The Pink Avengers resemble ordinary pigs almost completely. Despite having the ability to fly, they completely lack wings.