Currently changing hero costume (to vanilla or costumed version) modifies the hero everywhere, with only some exceptions (war defense team and tournament defense team after the lockdown). I suggest that player should be able to choose vanilla hero or costumed hero freely (separately, independently) for each and every team “use”.
There are couple of “urgency” levels for this:
The totally incomprehensible part of current behavior is that the class quest team selection modifies heroes elsewhere. Or other way around, changing hero elsewhere drops him/her out from class quest team.
Almost equally frustrating is similar behavior for defense teams, especially war defense team.
But actually I think that there is no reason for not allowing player to choose costumed or vanilla version for ANY team without affecting other teams. This would allow using roster teams as “presets” for various uses. Not as critical as, e.g., the class quest team, but why not fix this completely?