Wario's first major appearance in Nintendo history was the final boss of Super Mario Land 2. He stole Mario's castle, and the Italian plumber is back for revenge.
Wario certainly wasn't to give up Mario's house without a fight. He's quite tricky and fights you in three phases.
So I hope you know how to time your jumps.
But with skill, you send him crying home, but Wario at the time had no home, so Mario might actually be a terrible person on-paper.
But after Wario goes to search for a new place to live, Mario gets his castle back. Yay for Mario.