From the Super Mario Wiki
In 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, decide to build the Trash Smasher to help them clean up. Luigi winds up using the Trash Smasher alone to clean Brooklyn though, as Mario, while adding the finishing touches to the Trash Smasher, is mutated into a Koopa Zombie due to the exposure of King Koopa's litter.
Using the Trash Smasher, Luigi is able to clean all of Brooklyn and change all its Koopa Zombified-human inhabitants back to normal, as well as give the inhabitants of Brooklyn 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 board the Trash Smasher, which sprouts whirling helicopter blades, and begin to fly after Bowser and his Doomship; with Mario, Luigi and the Trash Smasher chasing him, the Koopa King quickly maneuvers his Doomship and tries to escape from his pursuers.