I think if it can use Fly, it should be allowed Defog and Roost.
My idea for the move:
Base Power: 40
Side effect: Freeze (15% chance), flinch (10% chance)
Additional info: Hits twice
Ingame desc: The user summons more of its kind, chills the air, and dive-bombs the enemy twice. May freeze and cause flinching.
Disclaimer: The above post may or may not have been made by a sane person.