It's extremely hard to find a way around that given the way the game is designed

Add an anti-assist structure to AR. Works the same way panic tower or the various movement-type schools do. Maybe just have it apply to movement assists like Repo, or maybe all assists so you can deal with stuff like Restore+. Doesn't remove the units from play entirely, but you run the risk that your dancers will be utterly useless if the enemy predicts your placements correctly. Should also lead to more variety besides "just stuff your units in the corners", all things considered.

Also I am surprised you didn't mention dancer Micaiah since she's your flair effective against Surtr and can probably one shot most relevant horses too

I should specify I'm mostly speaking in terms of defense teams. Offensive teams do have some more flexibility (but not a ton, due to needing a bonus unit for max score). I use H!Micaiah myself specifically because she's my favorite character, but I think Axura or Flylivia are 'better' for defense teams.