We have more info regarding the 3DS version of Mario and Sonic at the Rio Games! (Still no info about the WiiU version yet though.)
A new trailer for the 3DS version has been released, which gives us a wee bit more about the features in the game.
Some things to note, there are more characters confirmed to appear in this game, from the Sonic side, Omega, Eggman Nega, Cream, Sticks and Espio are confirmed playable, even the rest of the Deadly Six are confirmed to be there in the game! From the Mario side, Rosalina and the Koopalings are also confirmed playable.
There's a new poster as well, showing the characters-
Now for the features, the video shows that there could be some sort of minigame event (simular to the London Party feature in the London Games) and there's power ups that can be used in events that can help, (Such as different kinds of boxing gloves and golf clubs)
There are several Brazil related mii costumes for miis and another feature is that amiibo will also be used in the game!And all this is in the 3DS version. There's no news yet about the WiiU version at all.
What do you think about these features?
UPDATE: The official website is found, but it's all in japenese, it shows some sneak peeks of events: https://www.nintendo.co.jp/3ds/bgxj/about/index.html
Same gameplay footage courtesy of SonicWindBlue!
ANOTHER UPDATE: There's an article by Go Nintendo which gives more detail on which Amiibo can be used, and it also states that the 3DS version will have a Story Mode, in which you (as your mii) will pick between Team Mario and Team Sonic. Your choice will determine what events you can play. When you complete these events you will get either the Mario or Sonic costume for your mii!
The official japanese site also shows that some characters in the game are tied to specific events: https://www.nintendo.co.jp/3ds/bgxj/character/index.html