Which units should I use on a flier Team?

S!Y!Tiki, Myrrh, Cordelia, and Legendary Robin would be the units I’d use out of them.

Well personally you want to have a team that has atleast 1 representative each of the 3 colors, And have a sweeper and a tank. This is a basic Idea of balanced team, though you could just go with all offensive or all in defensive but I recommend to have a balanced team cause the other choices can sometimes mess you up.

I can't really suggest a team cause I don't know you're playstyle but I'll leave some generalise suggestions.
Team 1:Myrrh/Tiki/Cordelia/Hinoka(a pretty balanced team)
Team 2:Azura/Cordelia/Cherche/Summer Camilla(a sweeper team)
Team 3:Tiki/Myrrh/Robin/Cherche(a defensive team)
Team 4:Hinoka/Tiki/Ceada/Spring Camilla(each unit counters a unit type team.)

I frequently use fly-zura, Caeda, Camilla, Cordellia, fly hinoka, fly Kagero, from your list, and Clair, flying Nino, flying ninian, Elincia, flying Sanaki and flying Takumi. I really like the mobility of flyers, which is unparalleled in this game. Plus they get additional mobility skills, class buffs and many have bond skills that help when constantly bouncing around the map.Give each one Reposition or Drawback and you are golden.

Of your set, I would recommend:
fly-zura OR Camilla as a support unit to cover blues
Hinoka OR Kagero to help defeat mages during player phase
Tiki would be a great red unit, but also Caeda to cover many common Armored or Cav units.
Cordellia OR Summer Camilla to cover reds.

As long as you get one of each color, most flying units can synergize very well together.