Update 5/7: Wal-Mart now has removed the July 21 date and replaced it with a December 30 release date. All DVDs are typically released on Tuesdays, but December 30 is a Wednesday, so I am unsure on whether to trust Walmart's new date or not.
According to the official Walmart.com site, SCOOB! will be releasing on DVD and Blu-Ray on July 21. No DVD cover info or special features have been revealed yet, however, a free digital copy of the film will be available with purchase. You can pre-order the film at the above links now.