It is about toad, mario, luigie, and princess toadstool trying to save princess toadstools kingdom from King Koupa and his troupas. It is really cool. Half of thye show is real life and half of it is cartoon. (The cartoon is better.)
I recall watching it as a child in the early 90's - there was also a Link cartoon... I believe it was called the "Nintendo Power Hour" - 2 Nintendo shows back to back.