According to the description page on Amazon, Smash Bros. for Wii U will feature a Board Game Mode and Stage Builder:

The multiplayer showdown you know and love is now on the Wii U console! Take on all comers as Mario, Mega Man, Sonic, and more gaming greats. Or tap an amiibo to the Wii U GamePad controller to train it up by battling with or against it. You can even pit your amiibo against a friends’ to see how your training methods stack up. Whether you’re creating stages on the GamePad, competing in challenges crafted by Master Hand and Crazy Hand, or outwitting your opponents in a brand new board game mode, there’s no doubt that the ultimate Smash Bros. game has arrived.

This info comes days after Smash Bros. director, Masahiro Sakurai, hinted two new single-player modes for the Wii U version.

smash bros new modes 600x337 Leak: Smash Bros. Wii U features Stage Creator and Board Game Mode | VGLeaks 2.0Via | NeoGaf