The official site for Mario Sports Mix has had an interesting addition. Not only will Final Fantasy characters be featured in the game, but it looks like Dragon Quest might also be making a cameo.
While no characters have been confirmed, the copyright notice at the bottom of the page clearly mentions Dragon Quest and Final Fantasy.
If this is true, it'll be the first time all three franchises have been put together. Dragon Quest and Mario and Dragon Quest and Final Fantasy have been paired together before in Itadaki Street special editions.
Source: Official Site