This Mii is canon. That means this Mii actually exists in the Wii Sports/Wii Sports Resort/Wii Sports Club/Wii Fit/Wii Party/Wii Music games. However some of the information is fanon.
Boxer Dave is a Mii from Wii Fit, New Wii Sports, and New Wii Sports Resort.
He appears in Wii Fit's Rhythm Boxing as your trainer.
New Wii Sports
Nintendo decided to bring back Boxer Dave as an opponent in New Wii Sports. In Tennis, his level is 2700 and doubles with Enrique or Cathy. In Baseball his level is 2600-2818. In Boxing, he is a champion, with a level of 99,999,954-100,000,123!