Primarily with battles, skills, AI scripts and what not:
1) I plan on making all weapons 1 of 3~4 elements. Sort of like a 'Piercing, Blunt, Slashing, Magical'. Enemies will have a weakness two one of these elements (or to two of them with increased defenses to be a pseudo-resistance to).
2) Skills themselves will possess either Fire/Cold/Lightning/Poison elements and some (physical) skills will (and/or) possess Wind/Earth/Pearl/Water. Multiple double-weakness skills increases the chances of doing massive damage to specific enemies. (Late game, also increases the risk of nullifying abilities with immunities or absorption).
3) Particularly, I want to disable in-battle-revivals (phoenix down, life) to increase the challenge of trying not to die in battles. Particularly with (optional) bosses having instant-death attacks to decrease party size and increase difficulty as a battle progresses.
I also thought of having Rods be used as in-battle-items-only, particularly by having them heal a % of life (like a reverse demi, I'm pretty sure I can get that to work) so potions work better than a potion without being as effective as an X-potion or Elixir. Most notably is that most characters won't have every spell (See (4))
4) I managed to plan and divide my characters into dual-skilled or learner character types. Basically 'half' my characters do not possess the [Magic] command in replace of having two skills. (Edgar w/ SwordTech/Blitz, for example).
Learner type characters have unique weapons which learn spells only they can learn. (FF9 style). They also have the benefit of using Espers and any kind of Esper-taught-spells (which I'll probably limit to weak or expensive-mana-wise abilities so these guys aren't a tier above non-learners). All learners (Terra/Celes excluded for their natural-learning abilities) have 6~8 skills (6~8 weapons).
5) I also divided my characters into tank, caster or support heroes. Each one should have their own armors (which buff HP/MP like Red Cap, Green Baret and Bard's Hat) to emphasis their roles as tank or caster. Max HP is generally planned to be low end-game. (5000?)
6) I was thinking of giving every (most) weapons the Human-killer perk and altering enemies who have the human flag changed to just enemies like bosses so regular attacks do more damage but regular skills would not.
7) I tried making FF6ME give always wounded/stay wounded once wounded to try and enable 1/32 chance of using the limit breaks but that didn't work. I'm hoping someone will just make a hack like that for me
What wanted to do was replace the limit break animations with esper summon animations (also altering the summon animations to be appropriate/custom/unique to whatever I want these limit breaks to look like) to play out like a wicked-cool critical strike.
Have my Jump-character use palador (replace the image of palador), Terra using Fire 4.
Maybe alter Alexander into having that Shoop-da-whoop face and cast Megaflare.
Anyway, that's what I'm hoping to do. Progress is slow. I'm actually just collecting sprites to replace bosses to (hopefully) make some really cool battles. I'm having trouble thinking of an effective way to replace the existing images without having to 'fix' every monster sprite with every upload. (And I WILL do that if it comes to it).
I actually have this epic-sized Dragon sprite I found which I'll need to take up 3 monster locations to fit the screen. I actually have too many new sprites so I'll likely not be able to use them all AND remove images altogether to have enough bytes. (I'll probably attempt to import VERY small images to replace some big images, even replace General's sprite to share with Commando. Maybe have a few image-less sprites and just call 'em perma-vanished lol)