Complex sentence: Arizona, Arizona State, Central Oklahoma, and Oklahoma will join the league after participating as ACHA D-1 Independents, the four teams will join Colorado and Colorado State who are making the transition to ACHA D-1 from ACHA D-2.
Split into simpler sentences: Arizona, Arizona State, Central Oklahoma, and Oklahoma will join the league after participating as ACHA D-1 Independents. Those four schools will join Colorado and Colorado State who are making the transition to ACHA D-1 from ACHA D-2.