FFIV - Evilwall
FFV - Atamos
FFVIII - The Adel fight was annoying, though we played FFIX before it where the cage plant was absorbing HP from Garnet, so Adel was an easy fight, just a hard verison of the Garnet/Plant Cage fight.
FFIX - Ark, but that was because of some of the Oelivert party was magic based.