Butterfingers (The Super Mario Bros. Super Show!)
From the Super Mario Wiki
In The Super Mario Bros. Super Show! episode "Jungle Fever", Butterfingers, while aiding Dr. Sheldon in helping some of his Mushroom Person patients, bore witness to his kidnapping by King Koopa and his Shy Guy minions.
After Dr. Sheldon's kidnapping by King Koopa, Butterfingers was employed by Princess Toadstool to help her create a No-Itch Potion, which could be used on Mario, Luigi and Toad, who were suffering from extreme itchiness due to being doused in King Koopa's Koopa Strength Itching Powder. At first happy to help Princess Toadstool, Butterfingers eventually loses faith in herself when she accidentally created a duplication potion instead of a No-Itch Potion.
With Butterfingers unable to help Mario, Luigi and Toad, Princess Toadstool decided to go save Dr. Sheldon herself from King Koopa, much to Butterfingers protestation.
Later, after Princess Toadstool had traveled some distance through the Amazon Jungle, she was met with Butterfingers, who had decided to help Princess Toadstool in rescuing Dr. Sheldon from King Koopa. After being thanked by Princess Toadstool for deciding to help her, Butterfingers pointed-out a large amount of smoke emanating from a nearby stone structure, which she surmized was being created by Dr. Sheldon.
Climbing the stone structure, Princess Toadstool and Butterfingers saw Dr. Sheldon in the midst of creating a potion for King Koopa, willingly and without protestation. Shocked at what Dr. Sheldon was doing, Butterfinger, along with Princess Toadstool, were scared from their hiding place behind a pillar by a Cobrat, allowing King Koopa to see them.
As King Koopa has his Shy Guy minions restrain Princess Toadstool, Butterfingers begins to berate Dr. Sheldon, who is preparing to douse Princess Toadstool in a potion that will turn her to stone, saying that she officially resigns as his assistant. Ignoring Butterfingers, Dr. Sheldon, grabbing a bucket full of potion, threw it at Princess Toadstool, though not before telling her to duck.
Doing as Dr. Sheldon commanded, Princess Toadstool managed to bend over before Dr. Sheldon's potion hit her, allowing it to hit King Koopa instead. After King Koopa is doused in Dr. Sheldon's potion, Butterfingers, Princess Toadstool and King Koopa's Shy Guy henchmen can only watch in shock as King Koopa falls to the ground and begins to scratch himself crazily, proclaiming he's incredibly itchy; as King Koopa spasms on the ground, both Butterfingers and Princess Toadstool summarize that Dr. Sheldon had never joined King Koopa, he had been planning to dunk his Industrial Strength Itching Potion on him.
With King Koopa defeated, Dr. Sheldon, Butterfingers and Princess Toadstool returned to the village in the Amazon Jungle; Butterfingers was last seen watching as Dr. Sheldon gave his, in actuality, fake antidote to Mario, Luigi and Toad to cure their itchiness, spaghetti.