Nunu (and Willump): A little boy and his magic yeti from the Freljord. Who knows if this is allowed in dodgeball, but they can throw snowballs real good. I'm sure the skill translates.
Goro: The Prince of the Shokan and 4,000 year old half-human dragon man. Goro is one of the most powerful warriors in the history of Mortal Kombat. He also has 4 arms.
Patches O'Houlihan: 7-time ADAA All-Star and an ADAA champion who later became the dodgeball coach for the Average Joe's from the Average Joe's Gym. If you can dodge a wrench, you can dodge a ball.
Aroldis Chapman: American professional baseball relief pitcher who threw the fastest recorded pitch in baseball history at 106 MPH. His evasion may be weak but he's a glass cannon.
Flat Stanley: Children's book character. Stanley may not be strong enough to throw a dodgeball, but evasion is his middle name. Since he's flat he is easily able to avoid any incoming projectiles with ease.