Well there was the Super Mario Bros. Super Show which I remembered watching as a child back when the NES was still popular, too bad I didn't have a Super Nintendo back then or is it good? Anyway this was one of the shows I thought was pretty popular. It follows loosely from the computer games but it is a way better trip than that damn awful Super Mario movie (avert thine eyes from it).
Well it's not your trip to Mushroom Land all the time but it features King Bowser (called King Koopa here) with Super Mario Bros. 2 villains namely Mouser, Triclide the three headed snake, Birdos, Shy Guys and some of the standard villains like Koopa troopers and Goombas in their quest to take over various realities. Which King Koopa here becomes various story book characters and the Super Mario Bros. must stop him from rewriting history with the Princess Peach and Toad while of course, King Koopa does still have his on/off crush on the Princess Peach. In short, it was really a combination of two Super Mario shows while merging the roles of King Koopa with King Wart (the main villain in Super Mario Bros. 2).
A second season was produced based on Super Mario Bros. 3 which I thought was still pretty entertaining despite it not following the game story. I mean, while you don't have the mission to save the seven kings from their transformation, we do still have the battle against King Koopa and his supposed children.
Sadly the third season, based on Super Mario World imo was sucky. Great game but the cartoon was bad but still better than watching Super Mario movie!