The Trash Smasher is a large vehicle constructed from various random parts, such as a ♩ Block, several Warp Pipes and scrap metal. A mix between a tank and a vacuum cleaner, the vehicle is powerful enough to clean up all bits of waste, as well as counteract the effects of Bowser's Koopa trash that mutated Real World humans into Koopa Zombies, other creatures into his minions (seagulls into Paragoombas and fish into Spiny Cheep Cheeps), and even statues into reasonable facsimiles of the evil king himself, such as the Statue of Liberty.
During the events of The Adventures of Super Mario Bros. 3 episode "Recycled Koopa", Mario and Luigi, needing to clean up all of the mutating garbage Bowser is dumping on Brooklyn, let alone the entire city of New York and soon the rest of the Real World, decide to build the Trash Smasher to help them clean up and stop Koopa's dumping spree when Mario begins mutating into a Koopa Zombie himself. Luigi winds up using the Trash Smasher alone to clean up the city though, as Mario, while adding the finishing touches to the Trash Smasher, had finished mutating after being exposed to a large amount of Koopa's litter, which he fired all over the city with his Crud Cannon from the safety of his Doomship.
Using the Trash Smasher, Luigi is able to clean up the entire city and change all its Koopa Zombified-human inhabitants back to normal, as well as give the inhabitants of the city various appliances, which the Trash Smasher converts garbage into.
With all King Koopa's trash recycled into household appliances and Mario changed back to normal, Mario and Luigi modify the Trash Smasher to make it flight-capable, sprouting whirling helicopter blades, and chase after Bowser and his Doomship, as well as suck up all the garbage onboard before it can touch the city again; with Mario and Luigi chasing him in the Trash Smasher, the Koopa King quickly maneuvers his Doomship and tries to escape from his pursuers.