From the Super Mario Wiki
In The Adventures of Super Mario Bros. 3 episode "Dadzilla", Kootie Pie and Big Mouth, upon arriving in Hollywood, thought that Madzilla was their real father, due to the way that Bowser treated Kootie Pie earlier on. The two Koopalings used their Magic Scepters to bring a mechanical Madzilla to life.
Mario then devised a plan to build their own robot out of spare parts in the warehouse to play the role of Madzilla's Mom. In the interum, Madzilla was told to steal the Hollywood Bowl so that Big Mouth and Kootie Pie could perform their own concert. After the concert received a poor reception from the public, Madzilla picked up several innocent people, whom he threatened to toss in the Pacific Ocean. Before he could do so, Madzilla met up with Mario's robot, which he believed was his mother. While controlling Madzilla's Mom, Mario tricked "Junior"'s "children" into fleeing by insisting that everyone in their family must take naps so that they'll be rested to do their chores. Not wanting to stick around, Big Mouth and Kootie Pie ran back home.
She seems to be made out of a monster head, a dragon body and right leg, a gorilla's right arm, a sea monster's left arm, and a giant's left leg. She also has the power to exhale steam from her nostrils.