There are 4 playable characters in Super Mario 3D World, Toad, Luigi, Princess Peach and Mario, as they came from Super Mario Bros. 2. Each character has an unique ability. Like Luigi can do a long jump and Princess Peach can float in mid-air.
Toad, Princess Peach and Mario are playable at the start of the game but Luigi isn’t. yes you have to unlock it before to play with him. And also there is 5th playable character Rosalina, yes you can unlock the fifth character in Super Mario 3D World. Below you will find how you can unlock these charactes.
Unlock Luigi Bros.:
There are two ways you can unlock Luigi Bros. First is very easy you can buy it. Purchase Super Mario 3D World and have a save file on your Wii U, this will unlock Luigi Bros. and you can play with it.
Second way to unlock Luigi Bros. is to beat the Eight Worlds in Super Mario 3D World.
Rosalina is the fifth playable character in Super Mario 3D World from Super Mario Galaxy. You can unlock Rosalina by completing World Star-2. Rosalina jumps as high as Luigi and do a Spin Attack.