From what I understand about D&D 5 clerics, they are under one domain from their deity. However, despite that, the pantheon was made with Pathfinder's rules in mind (conversion of Phaeselis is going to be a beast). I'm going to crosspost this with Wizards of the Coast's message boards so I can get input from both sources.
This set of deities use a total of 6 cannon dragon gods from Wizards of the Coast, with 4 being original: Azazel, Naltharys, Freyr, and Typhon.
The Cannon ones are (from Monster Mythology): Io, Bahamut, Tiamat and Chronepsis. And from Races of the Dragon: Lendys and Tamara.
Observations, criticism, and questions welcomed!