Mecha-Bowser

Mecha Bowser (also known as Robo-Bowser or the Bowser-Bot to fans) is a huge robot that looks like King Bowser. In Super Mario Sunshine Mecha Bowser was found in Pinna Park, being controlled by Bowser Jr.. To fight him Mario must board a rollercoaster and fire Water Bombs (via FLUDD) at Mecha Bowser when he gets close enough. Mecha Bowser will attack by shooting Bullet Bill's at the heroes, and by breathing fire on the rollercoaster tracks. Eventually, Mecha Bowser is destroyed by Mario. Mecha Bowser also appeared in Mario Power Tennis. This lead players to assume that he was re-built by Bowser or Bowser Jr.. In this game he tilts the court. Later in Mario Party 5 he is a giant toy, that shoots characters out a canon.

A similar character called Bowser??? appears in Paper Mario.