The Super Mario Land 2 manual just states that Wario took over Mario's castle while Mario was of to save Daisy.
Tatanga working for Wario in SML2 strongly implies that the whole kidnapping plot in SML was just a distraction and that he was working for Wario all along, that's all it is thought
(I think) an implication and we will never get any official word on it since the Mario Land titles get pretty much sweeped under a rug by Nintendo and Tatanga aint' not coming back in a million years.