Bowser's Highway Showdown is mainly a liner level which is based on Bowser's castle. This all eventually leads to a very long platform where the players do battle against Bowser for the first time in the game.
- Green Star 1: Activate the Green Star Ring at near the first cannon to reveal eight green coins. Get those coins before the timer runs out to get the star.
- Green Star 2: To the right of the fourth cannon, be in Cat form to spin the wheel revealing a high ledge. Climb it to get the star.
- Green Star 3: Kick the soccer bomb to the third goomba tower to get the star.