We are using 12 characters right?
I was going to suggest eliminating someone from generation one since they already have been featured on the board graphic. I think Spinner and Emma both represent the series. They are a controversial romantic pairing though so don't place them near each other. Same as other characters in relationships, if this is possible. Or maybe that isn't a concern.
Shipping is a reason why Maya, Zoe, Miles, and Zig should all be included. But not placed near each other in the graphic. Unless Maya/Zoe and Miles/Zig, of course.
And this idea is going to get me in trouble I think if I start looking at the other characters.
But another thing that might please anti Spinner/Emma shippers is if the promo picture is from a different season of both of them so they don't look at the characters and think romance. For Sav and Holly J, I would chose a younger, ponytail sporting Holly J. And an older grade 12 scruffy Sav. Sav wasn't with Anya at her most stunning in their final season so this works.
Just a few thoughts.