Complex sentence: The Armstrong Falcons have a heated rivalry with the other team in the Robbinsdale School District, the Cooper Hawks as well as with neighboring high school teams, the Hopkins Royals, the Wayzata Trojans and the Minnetonka Skippers.
Split into simpler sentences: The Armstrong Falcons have a heated rivalry with the other team in the Robbinsdale School District, the Cooper Hawks. Other rivalries exist with: the Hopkins Royals, the Wayzata Trojans, and the Minnetonka Skippers.