The Poltergeist 3000 was the Vacuum Cleaner that allowed Luigi to suck up ghosts in Luigi's Mansion. It was also used for other various things like shaking furniture and sucking up coins. From them.
 Using The Elements
The Poltergeist 3000 was also able to use elements to help you through the game. You could use Fire to light Candles, use Ice to freeze foes and water, or use Water to put out candles.
 Other Appearances
The Poltergeist 3000 also made an appearance in Mario Power Tennis as Luigi's Save Power, where it would suck the Tennis Ball back to him.