"Mama Luigi" is the thirteenth and final episode of the Super Mario World animated series. It mostly takes place at the beginning of the show's story, serving as a prequel.
Inside the Dome Castle, Luigi is in the process of putting a somewhat resistant Yoshi to bed. Yoshi, not feeling tired, asks Luigi to tell him a story, more specifically, the story of how Luigi, Mario and Princess Toadstool met Yoshi.
Luigi goes on to tell the story: after banishing King Koopa from the Mushroom Kingdom, Mario, Luigi and Princess Toadstool decided to go on a vacation in Dinosaur World. While exploring Dinosaur World, they visit Dome City, which is oddly deserted. Looking around, Princess Toadstool is suddenly grabbed by a pair of Koopa Football Players. Before Mario or Luigi could save the Princess, they are attacked by a gang of enemies, consisting of a Koopa Wizard, a Magnum Bill and a Fire Sumo.
As Mario evades the Koopa Wizard and Magnum Bill, Luigi is attacked by the Fire Sumo, who proceeds to stomp the ground with enough force to tear open a large fissure. Unable to leap out of the way, Luigi accidentally stumbles into this fissure and is sent plummeting into the Lava Pits, where he apparently fell "for hours". Seeing nothing but lava below him, Luigi begins to panic; luckily, he manages to land on a magic balloon, which slows his descent and allows him to land on a Skull Raft. Unfortunately, this raft falls down a nearby waterfall of lava, plunging Luigi onto a small portion of land with several ? Blocks on it. Looking for an item that could perhaps help him, Luigi hits a nearby ? Block. After spurting out coins, the block does something unexpected: it releases a red-spotted egg. Grabbing this egg, Luigi is surprised when the egg hatches, producing a small green Yoshisaur, which proceeds to refer to Luigi as "mama".
Wandering the Lava Pits, Luigi feebly attempts to comfort the sobbing baby Yoshi. As he attempts to find out what is wrong with Yoshi, Luigi is approached by a purple Tyrannosaurus and a blue one. Thinking this pair of T-Rexs to be Yoshi's parents, Luigi hands the panicking Yoshi over to the Tyrannosauruses, only to quickly pull him away when the purple Tyrannosaurus attempts to eat him. The Tyrannosauruses, angered, try to eat both Luigi and Yoshi, who narrowly escape by jumping over a river of lava, using a Blargg as a stepping-stone.
Entering a Warp Pipe, Luigi and Yoshi find themselves dumped into the ocean. Underwater, they swim through a nearby tunnel, only to be chased by a recently awakened Rip Van Fish. Fleeing from the angered Rip Van Fish through the tunnel, Luigi and Yoshi narrowly avoid a swarm of Urchins. Exiting the underwater tunnel, Luigi and Yoshi lose the Rip Van Fish, who had fallen back asleep. While trying to swim to the surface of the water, they are attacked by a Blurp (this one lacks goggles) and a Torpedo Ted. Trying to escape the Torpedo Ted, Luigi and Yoshi are aided by several friendly Dolphins, who swim the two to shore. Once on a beach, Luigi begins to wring the water from his hat; as he is doing this though, the curious Yoshi waddles away. Noticing Yoshi had wandered away, Luigi begins to search for him.
Admiring some flowers, Yoshi fails to realize that a hungry Caterpillar is preparing to lunge at him. Jumping in just in time, Luigi manages to save Yoshi, only to be besieged by a swarm of caterpillars (or Wigglers) moments later. Oblivious to the danger present, Yoshi complains about being hungry while Luigi cries for help. Suddenly, Yoshi, unable to hold back his appetite, begins to eat all the caterpillars, defeating them, much to Luigi's relief.
Suddenly, Mario appears, having heard his brother's cries for help. Mistaking Yoshi for a dangerous beast, Mario lunges at him, only to be quickly eaten by Yoshi. Panicking once more, Luigi convinces Yoshi that Mario is not an enemy, and he spits him out. After telling Mario Yoshi is a friend, Yoshi proceeds to leap into Luigi's arms, calling him "mama" again, much to Mario's amusement. After he is finished laughing, Mario tells Luigi that he had escaped King Koopa's Coney Island Disco Palace, but was unable to aid the princess in escaping as well. Reaching the castle, Mario leads the others in through a nearby Warp Tube, which takes them the basement of Neon Castle, but it is dark inside. Mario and Luigi, working together, manage to hit a ? Block which activates a spotlight over them. Unfortunately, Yoshi wanders off while Mario and Luigi had worked on turning on the light.
Tracking Yoshi down, Mario and Luigi find Yoshi near a fireball-belching Gray Bowser Statue. As Mario and Luigi attempt to dodge the fireballs, Yoshi eats them and manages to shut down the statue by breathing fire on it. After destroying the statue, a secret passageway opens, which Yoshi ventures down, with Mario and Luigi following him. Entering a hallway, Yoshi nonchalantly walks down it, unaware of the large spikes shooting out of the ceiling. Pushing Yoshi out of the way of a spike, Luigi becomes flattened. As Yoshi runs off, Mario grabs the paper-thin Luigi and manages to return him to normal using a nearby magic balloon, then continue chasing Yoshi, who has leaped through the gate of a fence and opens a nearby door, meeting a Koopa Football Player.
Quickly climbing over the fence, Mario bashes the football player on the head, only for it to split into three. Tackling Mario and knocking him into Luigi, the Koopa Football Players are all eaten at once and subsequently spat out by Yoshi, who enters Bowser's throne room. Following Yoshi, who eats a piece of tapestry on the wall, into King Koopa's personal chambers, Mario and Luigi are attacked by a gang of Mechkoopas, who are directed by King Koopa, who had appeared from behind a pillar. While running from the Mechkoopas, Mario and Luigi discover Yoshi, who has eaten everything in King Koopa's throne room. Koopa enters, and, angered at them for his throne room being ruined, orders the Mechkoopas to attack them. However, they are saved by Yoshi, who eats the robot Koopas. Seeing how much Yoshi has eaten, Mario threatens King Koopa, saying that if he doesn't hand-over Princess Toadstool, Yoshi will eat all of Neon Castle, "piece by piece".
King Koopa, unfazed by this threat, states that he will build a new castle but Mario and Luigi will not build a new princess, because they will never gain the key needed to release Princess Toadstool, though Yoshi eats it out of his hand. Without his bargaining chip, Koopa vows revenge and flees into a nearby Warp Pipe. Praising Yoshi, Luigi quickly asks him if he can spit up the key, which he does, right into a nearby keyhole. Once the key enters this keyhole, Mario, Luigi, Yoshi and Princess Toadstool are suddenly transported to Dome City, safe and sound.
Having finished his story, Luigi notices Yoshi has fallen asleep. Tucking Yoshi in, Luigi says goodnight to him, with Yoshi mumbling "Goodnight Mama Luigi...hehe." Luigi then shrugs.
“Aw, do I have to go to bed so soon?”
Animation and continuity errors
Names in other languages