idk about the rest but
Fleur - "Bang Bang" or "Problem" seem like they could very feasibly be done by big band, so that
Jay - will probably do the Buble tediumfest that is Feeling Good
Stevi - Come Fly With Me, and I expect him to be dressed as a pilot with proper 'tash, and have a team of stewardess dancers
Andrea - "At Last" needs to be done tbh
Lauren - knowing Cheryl's ego she might well give Lauren a slow version of Crazy Stupid Love since there're trumpets in it