My preferred picks would be:

It would even be a full team. Caitlyn bot, Orianna mid, Quinn top, Taliyah jungle, and Sona support.
And yes, Caitlyn might have alot of skins, but that doesn't stop other champs to get more, so why should it stop her. She could be the intelligent and calculating member of the team, the strategist.
Orianna would be great because she could fulfill an interesting trope in my eyes. Kuudere, she might seem emotionless to strangers, but she actually cares alot about her friends. Maybe she got hurt on a mission and the first star was able to save her by giving her a magical, artificial body.
Quinn and Valor as magical girl and her familiar would fit too perfect to not give her a skin here.
Taliyah needs another skin, since the only one she got was because of worlds. I imagine her as himedere, acting like a princess (her sleeves would fit an outfit based on that).
And Sona fits the Star Guardians pretty well and was the only one coming to my mind for a support. ^^