You can get 5 Stars by your save profile in Super Mario 3D World. To get each star, complete the following challenges:

Beat Worlds 1-8
Get every Green Star in Worlds 1 through World Flower
Beat World Star, World Mushroom, and World Flower
Get every Green Star in the game
Get every Green Star, Gold Flagpole and Stamp (you must beat every world with every character, including Rosalina)