This game is a fighting game with all nintendo's characters like Mario, Kirby, Samus, Fox, Link, ecc.. Of course it can be played online. If you own a 3DS with a card you can use the portable console like a normal joypad for the WiiU.
I bought the custom package with Mario Amiibo included. The amiibo is a new release by Nintendo. It can be used with nintendo games for add some features like new weapons, custom clothes, extra energy and many more. The amiibo can transfer their features in the games via infrared port on the wiiu joypad.