I recommend you do what squaresoft did back in the day. That would be to just pour through old FF IV,V,VI sprites and edit the sheets. If you play Romancing Saga (another square game) you can see that all the battle mode sprites are just edits of FF sprites (line one is an an edit of Butz/Bartz)
now the sprites used out side of battle mode on the otherhand are actually quite simple.
in fact they usually only use two frames per animation. However there were lots of classes in the old FF games so there was still plenty of work to be done.
but if you want to know how to sprite the enemies you're on your own (from me anyway)