Update: We now have a video of the intro of the Wii U version as seen below:
We now also know that the Wii U version releases in Japan on June 23rd and will cost ¥5,700.
Just announced in the newest Nintendo Direct. Nintendo has announced that Mario & Sonic at the Rio 2016 Olympic Games on Wii U will release in NA and EU on June 24th.
We also have the final NA Wii U box shown above, as well as new screenshots below.