The Chum Bucket bucket helmet is a dark gray bucket with the Chum Bucket's initials written in red text in the center. This device is used to change the mindset of the fish wearing it, which the helmet covers their face when controlled.
Just like in the movie, Plankton uses the bucket helmet to take over the minds of the Bikini Bottomites.
The SpongeBob SquarePants Movie
Plankton uses the bucket helmet to take over the minds of the Bikini Bottomites. He then use them as slaves to make Bikini Bottom into Planktopolis but at the end SpongeBob destroys the bucket helmets, free the minds of the Bikini Bottomites, make Planktopolis back to be Bikini Bottom and Plankton is arrested with all back to normal.
The SpongeBob SquarePants Movie video game
Most enemies in the game and the background characters in Planktopolis wear mind-control bucket helmets.