Mario has never really been about plot. It's always been a game first and foremost. Yet despite this, it actually has some pretty decent continuity between games. For example, Professor Egadd, a character introduced in Luigi's Mansion, was the creator of Fludd in Super Mario Sunshine. Several characters like the Pianta's and Rosalina made many appearances in later Mario games. And there are references and callbacks to other Mario Platformers in the Mario RPGs. The only glaring exception to this seems to be Super Mario Galaxy 2 where it forgets the original ever happened and tells a retooled story.
That kind of continuity is very normal in cartoon shows with no continuous plot and childish comics... --- Cavorting about affixing Gogol Horns to houses does not constitute looking after an entire colony, Juju. -Dunban