I think giving an MVP abilities like the Masquerades do that go through FCP or more frequent dispell would remove those lazy GTB wearers.
Most of the ideas I've noticed in this thread are same ones I'd come up with. Some are already implemented, but I'd like to see more often
Some general ideas are:
-Wide masquerade ignorance/groomy/weakness/laziness/enervation/unlucky
-remove warg/cart/mech
-divest armor/shield/weapon/garment/acc/headgear (ignores FCP)
-break armor/shield/weapon/garment/acc/headgear (ignores FCP)
-reduce damage from certain skills (Cart cannon/acid bomb/dragon breath etc) for duration at expense of other skill doing more
-Dispell more often
-randomly outright KO someone
-constant ele changes both atk and armor
-switching agro and snapping to random party member (other than tank)
-retreating to heal/ full heal
-wide SP siphon
-wide HP siphon
-random coma
-a skill that reduces status resistances for a duration
-a skill that reduces ele resistances for a duration
-I liked aku's post about having strategic ways to kill the MVP with mazes and crap. good stuff.
-skill that reduces all party members hp to 1 and sp to 0.
-skill that reflects range damage to whole party
-skill that increases fixed cool downs
-skill that makes attacking/casting/doing anything cost zeny
-skill that prevents you from using items