Like all Palworld bosses, you should aim for headshots, but staying alive should be your main port of call. Utilize cover, time your shots well, and Saya & Selyne should fall in no time.
As for Alpha Pal bosses ... where you can find the legendary schematics in Palworld, and peep the table beyond that to see a list of all legendary schematics.
and where you can find all of them. The fastest flying Pal in Palworld is Jetragon. Unfortunately, Jetragon is one of the hardest Pals to catch; it can only be caught during the Alpha Boss fight ...