A new character has been announced for the arcade version of Pokken. It will also certainly come to the Wii U version as well.The new character revealed in a NicoNico stream is Darkrai, who will be playable in the arcade version on the 20th.
As well on the 20th, Wii U exclusive characters (Braxen, Garchomp, and Shadow Mewtwo), and stages will be added to the arcade version. A new mode will be added called Mission Panel where you compete in challenges during a period of time for bonuses. Last more trainer customization options will be available.
Darkrai will eventually be added to the Wii U since in the 1.3 patch for the game, files referring to Darkrai where found in the code.