The host, the eight invited guests, and another game were all confirmed.
http://www.nintendoworldreport.com/news/40404/more-details-announced-for-nintendo-world-championships
Nintendo has provided some more details about this Sunday's Nintendo World Championships in a video posted on their Youtube channel.
The second announced game for the championship is Splatoon, which according to the video is the first time the game has been played in a live tournament setting. Kevin Pereira, former Attack of the Show/Let's Ask America host, and currently of Hack My Life on U.S. cable network TruTV, will be hosting the event in Los Angeles.
The invited eight players were also announced:
- Speedrunners Sinister1, Cosmo, Bananas, Trihex, Essentia
- NES completionist TheMexicanRunner
- Smosh Games host Jovenshire
- Game Grumps host Arin
Justin Flynn, Andre (Black Nerd Comedy), and djWheat will call the action live from the Microsoft (previously Nokia) Theater starting at 3pm Pacific / 6pm Eastern on Sunday, with the previously announced pre-game show with the Treehouse starting 25 minutes before.