Mario Tennis Aces is an upcoming tennis game for the Nintendo Switch, developed by Camelot Software Planning. The game will release on June 22, 2018 in North America, Europe, Australia, and Japan.
Daisy was originally leaked (along with Yoshi, Rosalina, and Bowser) in screenshots posted before the March 2018 Nintendo Direct. She was officially confirmed in said Direct.
Compared to Mario Tennis: Ultra Smash, Daisy hasn't changed that much physically. She now wears an orange and yellow wristband on her right arm and also wears new sneakers. The Nintendo Direct confirms Daisy to be an All-Around character, just like in Mario Tennis: Ultra Smash and the tennis mode of Mario Sports Superstars.