I have crafted a team that I believe to be the most effective for dealing with all aspects of Miitopia's post-game. So if you are struggling, this team should give you an easy time.
Player should be an Elf. Elves are very good in the hands of a player. They might not look all that cool, but trust me. They are really OP. They have a high damaging aoe magic attack. They can stunlock normal enemies. They have an aoe heal and an mp restoration move. They have a counter that can activate on basic attacks. They are slow and frail but they make up for that with Forest Aegis. It only costs 3 mp, and you can use it on all your party members. It halves all the damage you take. You're basically immortal. This is the key to dealing with the towers.
Cleric is next. You get the best AOE heals in the game, a one shot move that usually works on certain enemies. And a guaranteed revive move. You're team is even more immortal than it was before. Make sure you prioritize the safety of your Cleric.
Scientists will prove useful as the 3rd member. You get massive AOE magic attack damage. You get a heal that also restores MP. So you're more immortal now. Basic attacks can become AOE moves. And the main reason you should have a scientist is for Safety Mask. You now have an effective counter against status effects.
Vampire is the last one. High health so even more immortal. They can revive themselves so you get more immortality. And they can use Enthrall to make other party members even more immortal than they already were. You have great AOE physical damage. And a good single target magic attack that hits the enemies physical defense stat. So you have a fiend killer on your team.
So this team has it all. Physical Damage, Magic Damage, Physical and Magical AOE damage, MP restoration options, Single Target Healing, AOE healing options, a skill that makes everyone super tanky, 2 methods to revive team members (one before and after death), and a counter to status effects. You have it all. If you want to clear this post-game without trying. I recommend this team. Plus it's kinda fun, at least in my opinion.