Balloon Berries are items first encountered in the Haunted Towers and later, the Treacherous Mansion of Luigi's Mansion: Dark Moon. These items possess a special ability: if Luigi vacuums a berry, it will give him the power to fly around, by sucking in or blasting out air.
The power from the Balloon Berries will only last until either Luigi touches something spiky, something hot or until he sucks up the berry, otherwise it'll stay stuck to the Poltergust 5000's nozzle. Another Balloon Berry will generate from the same spot if sucked by the Poltergust. Another variant of the berry is the Golden Balloon Berry, which is similar but generates a trail of floating coins. Golden Balloon Berries only spawn once in their respective spots, and a regular berry will generate if the golden one is used. If Luigi does collect all the coins, he is rewarded with a chest that will contain either treasure, a gem or in the case of the Treacherous Mansion's Dark Age Exhibit, a Boo.