Flier Emblem help

Since you have a green and a blue.
then i would recommend to have a red( the 4th spot can be anyone)
I recommend SY!Tiki since she is really fast and can take a hit and she's red.
the 4th spot can be anyone the first 3 spots are important since you need a balanced team and the 4th spot can be a character you like or has a specific role in the team.

Either go for S!Takumi or WF!Hinoka.

I have 2 flier teams. The first is based around a blade tome, a raven tome, and 2 dancers. Basically, you take advantage of the crazy buffs to the blade tome and use the raventome + triangle adept to check most archers. My blade user is S corrin, but S Tana could work really well. S Camilla is my raventome, and my dancers are Airzura and Olivia, but Ninian can work and wield a blade tome to help her damage output.
The Second is entirely melee. Im currently building up a Beruka who is the star of the team. She relies on buffs and wards to essentially take no physical damage. I use NY Camilla, Airzura (but Ninian works too, if not better), and regular Hinoka, but you could sub in WF Hinoka to get the same mobility advantages.
If you're already using Ninian and Cherche, and are prepared for some heavy investment, I'd recommend giving Ninian a blade tome, adding S Camilla with a raventome, and then with WF Hinoka for Cherche's mobility or another blade user, most probably S Tana.