Role in the film
According to Snowball, The Flushed Pets is like a club, but with biting and scratching. They live in an underground lair locates in the sewers of New York, where more animals that are unlikely to be pets are also residents and are presumably the members of the gang. Though they don't have a known specific plan to take revenge on all pets and humans, they do appear more when they want to rescue members or take revenge on who hurt their members. To be a recognized member of The Flushed Pets, one needs to be bitten by a sacred and half-blinded Viper that lives in a metal pipe in normal times, though it remains unclear if any of known members have been bit by Viper.
Out of unknown reason, Ripper, one of the main helpers of Snowball, was caught by Animal Control, so Snowball goes to save him by hijacking the truck Rippers at with Tattoo and Dragon. They bring Max and Duke as well after they are convinced that the two dogs aren't pets. But Snowball soon finds out that Max and Duke are domesticated by informed by The Alley Cats, he orders his minions to catch them, but eventually causes the death of Viper. So they rush to catch them, but Max and Duke escapes, so Snowball goes back and makes a plan to catch these two dogs in Brooklyn. In the process, they almost catch Max's neighbors, who are led by Pops in search of signs of missing Max; nevertheless, Derick catches Norman after noticing he weaves out from a pipe.
Though Snowball finds Max in Brooklyn, Tattoo and Dragon are caught by Animal Control, so he and Max drives a bus to chase the truck, but he passes out after the bus and the truck crash at Brooklyn Bridge. Derick thinks that Max catches Snowball so all animals of The Flushed Pets swarm from nowhere, which horrifies many of the pedestrians. When they are about to attack, Gidget joins the combat and saves Max from being attacked. However, the truck along with Max and Duke falls into the river, so Snowball dives and finds the floating key to Duke's cage. The successful rescue makes all animals on the bridge cheers, and then Tattoo finds a taxi, bring the animals back to Manhattan.
Snowball intends to resume the mission before he is adopted by a girl called Molly while other his members hide in the sewer. It can be assumed that The Flushed Pets stops their revenging plan because they later attend a dance party held in Leonard's Apartment or that they are searching a new leader before they can strike again.
- It's unknown if they fully redeemed themselves since Snowball redeemed himself