Super Smash Bros. 3DS is a series of cross over fighting game featuring Nintendo's "all-stars" iconic characters, various stages and items as well. It is a sequel of the Super Smash Bros. game series. There are characters such as Mario, Kirby, Pikachu, Sonic and many others.
Each character in this game has distinct and unique moves and have the ability of using various items which may appear during fights. There are different exclusive stages which are been offered at every level of the game.
Dream Land (Kirby series)
To unlock the Dream Land stage you don't have to worry because it is as easy as using Kirby's Final Smash. Like with Pac- Maze, it might be quite easier for you to enter Training mode and spawn a Smash Ball there.
Mute City (F-Zero series)
Continuing this interesting trend we're seeing in Super Smash Bros for 3DS, it is seen that Mute City makes its way into the game as an unlockable stage i.e a stage which is quite hard to unlock a difficult stage to pass on. You can only unlock this stage, when you win three Smash Mode battles using Captain Falcon
Flat Zone 2 (Game & Watch series)
Last but certainly not the least, is Flat Zone 2. To unlock this stage, all you need to do is unlock Mr. Game & Watch as a character. But however, the stage will only get unlocked when you would have completed the first page of Challenges (even though you would have already unlocked Mr. Game & Watch).
These were all the unlockable stages that Super Smash Bros for 3DS is offering gamers for now.