From the Super Mario Wiki, the Mario encyclopedia
The Mushroom Colony is only seen in The Super Mario Bros. Super Show! episode "Star Koopa". Darth Koopa wants the Mushroom Colonists to surrender their planet to him while threatening to destroy it with his Birdo Ray if they failed to comply.
After escaping from Koop Star aboard a Garbage Pod, Mario, Luigi, Princess Toadstool and Toad crash land on the Mushroom Colonists' planet, where, after fighting off a Pokey and Cobrat, make it to the Mushroom Colony, where colonist Obi-Wan Toadi quickly devises a plan to penetrate Koop Star with Mushroom Starfighters. As Mario succeeds in blowing up Koop Star, the Mushroom Colony, along with the rest of the planet, is saved from the Birdo Ray.