Without buying the 3DS version
Before this week, Super Smash Bros. players who wanted to use their 3DS to control the Wii U version of the game needed a full portable copy — but not anymore. As of right now, you can go to the eShop and download the “Smash Controller” app for $0.99, which will let you link your 3DS to the game.
It’s something that should have been available on day one, but hey, it’s here now.