From the Super Mario Wiki
In The Super Mario Bros. Super Show! episode "Mario and Joliet", Joliet and her fiancee, Romano sent word to Princess Toadstool, Mario, Luigi and Toad asking them to come to the Land of Romance. Eventually, Joliet and Romano met Princess Toadstool, Toad, Luigi and Mario in the tunnels beneath the Land of Romance after Princess Toadstool, Toad, Luigi and Mario had fallen through the streets of the Land of Romance and into these tunnels while being attacked by an Albatoss and Bob-omb.
Greeting Mario, Luigi, Toad and Princess Toadstool, Joliet and Romano told them that they were supposed to be wedded, only for King Koopa to appear in the Land of Romance and begin a violent feud between their fathers, who refused to allow Joliet and Romano to be married. After hearing this story, Princess Toadstool decides to simply order Romano's father and Joliet's father to allow Joliet and Romano to marry. After some difficulty, Princess Toadstool does succeed in making Joliet's father and Romano's father agree to allow Joliet and Romano to be wedded.
Later, in the church where she was to marry Romano, Joliet, as she prepared for her wedding, was alerted by Toad to hurry; after being told by Toad to hurry, Joliet, while singing to herself, is suddenly attacked by an Albatoss which had swooped into her room. Despite Toad trying to fight it, the Albatoss succeeds in capturing Joliet, who the Albatoss proceeded to take to it's master, King Koopa.
Later, after a having attempted a rescue of her, Romano, Toad, Mario, Luigi and Princess Toadstool were captured by an Albatoss minion of King Koopa and were placed in the same prison cell as Joliet by King Koopa and his henchman, Grunt. After getting rid of Grunt, by tricking him into lifting so many weights that he was sent crashing through the floor, Princess Toadstool notices that the Joiliet's wedding bouquet is composed entirely of Fire Flowers. Noticing this as well, Mario grabs ahold of Joliet's Fire Flower bouquet, which transforms him into Super Mario. Using his newfound powers, Mario manages to blast down the door of the prison cell he, Luigi, Toad, Romano, Joliet and Princess Toadstool. As they escape though, Mario, Luigi, Toad, Princess Toadstool, Romano and Joliet encounter King Koopa and his Koopa Pack, consisting of Koopa Troopa.
As Mario distracts these approaching Koopa Troopas, Romano, Joliet, Luigi, Toad and Princess Toadstool, using the door of their former cell and some of Grunt's weights, managed to make a vehicle. Using this newfound mode of transportation, Romano, Joliet, Toad, Luigi, Princess Toadstool, after picking-up Mario, managed to escape from King Koopa's castle.
After this adventure, Mario, Luigi, Toad, Princess Toadstool, Romano and Joliet returned to the ruined church of the Land of Romance, where Romano and Joliet were finally wedded.