Hot on the heels of its Midnight Purple 3DS announcement, Nintendo has detailed more features for Mario Tennis Open -- set to launch the same day as the new color. The announcement includes more info on the game's multiplayer, plus some unlockable characters.

Multiplayer includes both competitive and cooperative modes, locally or online. You can win Victory Medals from these opponents and build up your Open Match standings, and the game will support a monthly leaderboard as well. The game will also let you play against virtual versions of people you StreetPass with, in competitive matches or cooperative Ring Shot challenges. Your Mii will be shared via StreetPass too, including peacocking with the accessories you've equipped to improve the little fella's tennis game.

Character unlocks will be supported through two methods. Some will be unlocked through gameplay, while others will rely on special QR codes. A few of the characters were teased in today's announcement: Luma, Baby Mario, and Dry Bowser. You'd think those first two would have a distinct height disadvantage for tennis, but maybe they make up for it with moxie.

Mario Tennis Open is hitting the 3DS on May 20.