Successfully complete the game. You can hit the red "M" block that now appears at the start of each level to make Luigi move like Mario in New Super Mario Bros U.
After beating the last stage, a red block with the letter "M" on it appears at the beginning of every stage.Hitting it makes Luigi's movement physics the same as Mario's were in the New Super Mario Bros U. This does not affect Nabbit.Effect last until you exit the stage.No penalties occur when using the block.
Hold ZL when selecting a level in single player mode. Note: Luigi will return as the main character after the level or if Nabbit dies.