King Koopa goes into the fast food business and his food is a hit with everyone in Dome City, except for the Princess. But no one knows that Koopa sneaked in a side effect for those who eat his Egg Scoopa Koopa sandwiches, turning them into Chickadactyls. Only Mario and the Princess remain unchanged so it's up to them to stop Koopa.

Kootie Pie steals Dome City's Mama Fireplant to keep her warm in her Ice palace. Mario and company race to retrieve the fireplant before the residents of Dome City freeze.

Mario tries to make the cave people's lives better by inventing the wheel for them, which leads to cars and way too many traffic problems. The now angry cave people kick the Mario Brothers out of the city just before King Koopa launches an attack.

Despite King Koopa's objections, Hip and Hop go to Princess Toadstool's school and cause trouble.

Mario invents the telephone for the cave people. He soon regrets it, however, when he and Luigi have to keep protecting the cave people, who are spending all their time talking on the phone.

Mario and company visit King Koopa, Big Mouth and Kootie Pie's circus, where they discover the audience is going to become some hungry dinosaurs' next meal.

Mario, Luigi and the Princess are captured by a Magikoopa named Wizenheimer. It's up to Yoshi and Oogtar to enter his haunted house to save them.

After Mario and Luigi yell at him, Yoshi runs away. He then meets the Dino Riders, who are planning to capture the Mario Brothers to get gold coins from King Koopa.

During a football game with the cave people, Luigi gets turned into an egg by a Magikoopa. When Bully and Cheatsy take him back to Neon Castle, Mario and Yoshi have to play a football game against the Koopalings to get him back.

Mario brings Christmas to Dome City to encourage the cave people to act nicer toward each other. When Oogtar tries to get his hands on the best presents, though, he winds up getting taken by the present stealing King Koopa. It's up to Mario to save Christmas for Dome City.

King Koopa introduces Dinosaur Land to television and plants a Magikoopa inside each set to hypnotize the viewers.

Luigi teaches the cave people about farming and growing their own food before the coming winter. But when the crops are stolen by Cheatsy, it's up to Mario, Luigi and Yoshi to get them back.

Luigi tells Yoshi about the Mario Brothers and Princess Toadstool's first adventure in Dinosaur Land.