The Wii U version of Mass Effect 3 by developer Straight Right will include not only the Extended Cut ending DLC, but also From Ashes as revealed by a press release by Nintendo UK.
From Ashes features an extra party member in Javik, the last surviving Prothean and the Prothean Particle Rifle. It also gives new outfits for all party members. It was released as a day one DLC which caused a lot of backlash from gamers.
It will also feature an interactive backstory for players which covers events from the first two games of the series.