Super Smash Bros. for Nintendo 3DS and Wii U

Super Smash Bros. for Nintendo 3DS and Wii U is a fighting video game for the Nintendo 3DS and Wii U, hence the title, being developed by Sora Ltd. and Bandai Namco Games and published by Nintendo. It's the fourth title of Super Smash Bros. series of games, in which characters from various Nintendo franchises fight against each other. The Nintendo 3DS version was released on October 3, 2014, and the Wii U version was released in November 21, 2014.

Two versions of the game were released, one for Nintendo 3DS and the other for Wii U. The Wii U version is presented in high-definition visuals, while the Nintendo 3DS version features characters with black outlines, which can be toggled on and off.

The Wii U version is compatible with the amiibo platform. An update on February 10, 2015 added amiibo support on the 3DS version. They are compatible with New Nintendo 3DS systems and via an NFC sensor device for the older Nintendo 3DS systems, these sensors will be sold separately.

Functionality
In these games, amiibo are used as a sort of training partner. Your figure keeps your stats in its memory and learns the way you play so it can better counteract your strategies. You can also adjust its stats and give it special equipment or moves. It can also be used against a human opponent in the middle of a match.

Trivia

 * Super Smash Bros. for Wii U and 3DS has the largest amiibo set to date, and from what Masahiro Sakurai said, it probably won't be beaten. Ever.