Nintendo has said next to nothing about a game known as Pokemon Rumble World, but apparently it exists as we have discovered thanks to an age classification provided by the Australian Classification Board. It is only today this has appeared and of all the Pokemon Rumble games released I can't find anything like this one.
Of course because we haven't seen an official announcement we know next to nothing about this game and the classification board does not tell us much. From the general note provided by the classification we know the game is being brought to us by Ambrella who worked on the series previous entries, along with this there would also appear to be online interactivity.
The listing also suggests the game will hit multiple platforms, so I could assume the game is coming to the Wii U and 3DS, however considering recent announcements I think mobile devices might not be out of the question. Personally I hope the latter is not true, but it is a very real possibility now.