Dumbo is a CPU Mii and is bad in all sports.
Dumbo's level in Tennis is -2. His level in Baseball is 1 and has himself, Elisa, Emma, Luca, Akira, Matt, Kentaro, Abby, and Jessie. His level in Boxing, though, is 57.
Wii Sports Resort
His level in Swordplay Duel and Speed Slice is 3. His level in Basketball is -1 and plays with Miguel and Geoos. His level in Table Tennis is 5.