I think a good idea would be a shapeshifting class~
I used that type of class in in mmo once before and its so much fun to use and gives you many different options in ways of play.
To adapt it into a final fantasy format, I'll put it this way.
Say when you reach level 30 - instead of getting a 'job' as it were, you learn a new way to shapeshift.
Like you could pick to shapeshift into a certain animal which gives you tanking benefits, dps benefits or healing benefits.
Kinda like being a summoner except you ARE the pet.
I doubt something like this would ever be put into final fantasy, it seems like it would be a total nightmare when it came to dungeons (like... you'd have to lock in on an animal or something), and might make it too unfair on other characters - but hey, I can dream, right?
