There are 4 worlds in all, each having 8 levels.
World 1- Dark Castle. Boss- Princess Peach
World 2- Stone Fortress. Boss- Wario
World 3- Waluigi Casino. Boss- Waluigi
World 4- Deep Space. Boss (Final Boss)- Tatanga
In world 1 level 6, there is a secret passage to the Minus World. It is only hidden on the advanced mode for players who are good at the game, basically players above 13 because of the violent hell that the minus world is.