Waldo the Wizard
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Waldo the Wizard, also known simply as Waldo, is a wizard who lives in his own castle, which is presumably located either in or near the Mushroom Kingdom. Waldo speaks with a British accent, and as such, uses terms such as "jolly" and "cad." He is also shown to be rather skilled, as he can cast spells or create potions just by merely waving his hands around, and is also capable of flying.
At some point, King Koopa discovered Waldo's castle, and succeeded in banishing him from it. Assuming it actually belonged to King Koopa, Mario, Luigi, Princess Toadstool and Toad attempted to foil King Koopa there, but were captured and imprisoned in the dungeon by Mouser. It was there that Waldo revealed himself, by pouring his Magic Shrink Potion onto Mouser and two Koopa Troopas, shrinking them.
Waldo then introduced himself to Mario's group, and while using his magic to free them from their shackles, explained his situation to them and declared that he would reclaim his castle from King Koopa using his magic. The excited Toad, who grabbed his Magic Shrink Potion in hope that he could use it on King Koopa. Joining Mario's group, Waldo followed them out of the dungeon, where Toad came close to using the potion on King Koopa, but instead hit Mario and Luigi with it, shrinking them instead. Before Waldo could react, King Koopa lassoed himself, Princess Toadstool and Toad with a sausage rope. As Waldo could not move his arms at this point, he was unable to cast a spell that could aid them.
Waldo, Princess Toadstool and Toad soon found themselves each tied to a lounge chair with rope, and could do little more than watch as King Koopa and the Koopa Troopa chased Mario and Luigi across the lawn of the courtyard. After Mario and Luigi ran into the greenhouse, Princess Toadstool discovered that she, Waldo and Toad could move around if they shook themselves, as the chairs had wheels. By shaking themselves, they gained enough momentum to crash into the Koopa Troopas, breaking the chairs in the process.
Able to use his magic again, Waldo conjured up a Magic Growing Potion which Toad slipped inside the spray gun that King Koopa was using to spray pesticide at Mario and Luigi with. When King Koopa sprayed Mario and Luigi with the wrong potion, they not only returned to their normal sizes, but the vegetables surrounding them grew as well.
After Mario and Luigi used the vegetables to scare King Koopa and the Koopa Troopas out of Waldo's castle, Waldo conjured up a large, winged boot which proceeded to chase after King Koopa and repeatedly kicked him as he ran for his life. With the Koopa Pack no longer a threat, Waldo was once again able to live peacefully in his castle.