Camilla isn’t a bad choice at all for a flier team, but isn’t strictly necessary
Fliers can work with most movement types well, and generally are supportive movement-enhancing units to help other units over terrain like forests, mountains, water, and trenches.
Alternatively, they are quite good in a hit-and-run playstyle where units engage in one or two combats per phase and use their mobility to retreat out of enemy range.
All-Flier teams are generally better on maps with terrain that limits movement, as they can abuse their mobility to evade and attack the other team with smaller repercussions.
Mixed teams generally use the flier as either a movement support/mobile attacker, or both. They help circumvent some issues the other movement types have while compensating with general strength