In my infiltration of a palace I started to notice a bit of a trend with enemies I am fighting. More and more the enemies are either having hard to use weaknesses or the even worse case no weaknesses at all. I have ran into an extremely difficult set of enemies in a palace that consists of one or two enemies that are resistant to all physical attacks, and have no magical weaknesses at all. These enemies are nearly always backed up with healer enemies, which honestly don't pose too much of a threat but here is my problem.
How can I deal with these types of enemies with no weaknesses without having my party getting slaughtered while these enemies run rampant unable to be knocked down by anything besides a lucky critical.