I’ve defended the Free Will Defense (FWD) against some bad objections, and there are lots of them: the argument is among the most frequently misunderstood, even among people who worry about this sort of thing. But I think there is a decisive objection to the argument, and that Mackie was on to it already in ‘Evil and Omnipotence’.
. . . there was open to [God] the obviously better possibility of making beings who would act freely but always go right. Clearly his failure to avail himself of this possibility is inconsistent with his being omnipotent and wholly good (my emphasis).
Plantinga’s FWD aims to show that, possibly, God cannot eliminate all evil: possibly, every creatable being is transworld depraved, so, possibly, no matter which world God actualizes (except of course for a world including no sentient, rational, free beings) there will be some evil (someone will do something wrong).