Topper

Topper is the first boss in the game. He is met in Cap Kingdom,

Fights

Topper is first met in Cap Kingdom where he has 2 Phases. In Bowser's Kingdom and Dark Side he has 3 Phases. To end a phase Mario needs to jump on his head while all of Toppers Hats are knocked off. This is achieved by either throwing cappy at him or jumping on him. Knocked off hats remain in the arena until they are again either jumped on or by hit by cappy. Hats deal damage to Mario. As long as Topper still has 1 or more hats he is running towards Mario but as soon as he looses all of them he tries to escape Mario. When he gets hit by Cappy while not having any hats he stops running.