From the Super Mario Wiki
The Quirks are an alien species originating from The Super Mario Bros. Super Show!. Quirks are humanoid in appearance and have light-green skin; they also have two trumpet-like noses jutting from their faces. The Quirks are the only known, native inhabitants of the planet Quirk.
The Super Mario Bros. Super Show! episode "Stars in Their Eyes", it is revealed that the Quirks have been enslaved by the evil Moon Man Koopa, Astro Mouser and their Koopa Troopa minions; the Quirks are forced to mine the rocks of Quirk and transport them to Moon Man Koopa's Quirk Factory.
After a lot of hard work, Mario, Luigi, Toad and Princess Toadstool manage to repair their spaceship with help from the Quirks and battle Moon Man Koopa in his spaceship. After a long and narrow battle, Mario, Luigi, Toad and Princess Toadstool manage to beat Moon Man Koopa, who next tries to land back on the planet Quirk.
Unfortunately for Moon Man Koopa, the Quirks, having been inspired by Mario, Luigi, Toad and Princess Toadstool, rebel against Moon Man Koopa and hum a song loud enough through their noses to cause Moon Man Koopa's Spaceship to malfunction internally. The Quirks, free from Moon Man Koopa's and his henchmen's rule, are last seen waving goodbye to Mario, Luigi, Toad and Princess Toadstool as they zoom away in their spaceship.