Since they will likely stick with three person battles only, and since they walk a bit ahead or a bit behind you, I want in universe justification about what the other characters are doing (as in, they are elsewhere, so as to justify why they aren't helping you fight). Hell, since they are cribbing a lot from a lot of the final fantasy mainline games in between 7 and 7R, they should do ATEs like 9.
For example, going to Kalm from the Midgar outskirts. Takes two seconds in the original game, but for a variety of reasons could take longer this time. Depending on who the two person team is, you could have awesome scenes:
Barret and Red: Comedy (TFS maaaay have corrupted me here).
Tifa and Aerith: Getting to know each other and establish their own close friendship.
Aerith and Red: Discussing how weird Hojo is and getting to know each other fresh.
Barret and Aerith: Talking about Marlene and Barret finally getting to say thanks.
Barret and Tifa: Discussing the future of the resistance, Cloud's leadership, recruitment opportunities...
Tifa and Red: ....no clue about this one, but it could be nice.