Is it possible for the arenas to be changed to allow any of the required characters, and not just a specific one?
I noticed this previously with the Divine Champions and now with The Best There Is, but sometimes the retaliation will land on an arena where you either don’t have the required character or it isn’t really viable to use.
Just now, I had a retaliation available in The Best There Is, but on the arena requiring X-Force Wolverine. I’ve got him at level 30 with 1 green cover. Considering my opponent was fielding a group of 3 level 85s including an 85 Astonishing X-Men Wolverine, I didn’t feel my odds were good, so I just skipped the retaliation.
If I’d been able to use my own 85 Wolverine, I would have been much more inclined to accept the fight.