Instructions
Speak to the Pixl at the beginning of the level, who will offer advice on rescuing Tippi. This information will be important later in the game.
Walk to the right until you reach two red pipes with a gap between them. Jump into the chasm to reach World 1-2 from "Super Mario Bros."
Walk to the right to reach the pipe at the end of the level. Instead of entering the pipe, jump on a platform near the pipe and ride it to the top of the board. Jump onto the top of the ceiling and continue to the right until you find three pipes.
Jump into the middle pipe to emerge back on level 3-1. Press the "1" button to drop Boomer at the red "X" on the castle wall to blow it up and encounter Bowser.
Use Boomer to damage Bowser. Avoid Bowser's fire breath and continue attacking until he is defeated. After the battle, Bowser will agree to join your party.