Nintendo has released the next update for Smash Brothers Wii U and 3DS. The update adds the normal stability fixes and adds sharing features. The sharing features allows for sharing of custom stages and pictures through the internet and Miiverse.

This update also allows access to the Mewtwo DLC. Those who registered both the Wii U and 3DS versions of Smash should land their downloads codes in their email soon.

Source

Update: Nintendo has released the official release notes for this update.

Ver. 1.0.6 [Released 04/15/15]

Users will be able to purchase DLC from Nintendo eShop.

Share mode has been added:

Users will be able to post photos, replay data, Mii Fighter data, and Custom stage data to the official server to share with other users around the world. Users will also be able to search and download the content as well

*Users can only post their own content. Content posted to the server will be deleted after 30 days.

Users will be able to post photos and Custom stages to Miiverse from within the game (Photos will be posted to the official Snapshot Sharing Community and Custom stages will be posted to the official Stage Sharing Community

Users can download data from the server to Super Smash Bros. for Wii U if there is an activation button in the images posted on Miiverse.

Users will be able to share and exchange photos, replay data, Mii Fighter data, and Custom stage data with users on their Nintendo 3DS Friend List.

Content will be received when the Nintendo 3DS is connected to the Internet
It may take some time to receive the data

Content uploaded to the server will be deleted from the server after 30 days.

Added 6 new 8-Player Stages

Omega Stages:

Delfino Plaza
Port Town Aero Dive
Woolly World
Orbital Gate Assault
Wii Fit Studio
Pilotwings

Adjustments have also been made to balance the game and make for a more pleasant gaming experience.