this game was released after Bowser’s Inside Story (Original). This game also features some new things to the series like badges.
These badges would give extra perks in battle. For example one badge would make you invincible for three hits, and after that you were vulnerable. There also many others you could use.
In this game you would travel into the dream world, and one of the things you would do was have giant battles. Those battles were so big you would have to turn your 3DS sideways to play!
This was activated by Luigi sleeping on a pilo, and the world was a 2D world. These areas were the same in the normal world, but with different people and aspects.
Turns out in the dream world there is a dreamy Luigi. He is Luigi except there are a lot of them. So much that when you collect attack pieces they have their own attacks. During the Dream world Luigi would have special moves he could do to get through different areas!
Overall the game is long and fun. There is a lot of content and good music that makes this game good. I suggest you to get it!