I say for battles amke more options beyond just attack, defend, and such. Also more placement decisions. I would also like to see much more battle situations appear again, like pincer atatck (of both you or the enemy) and all that stuff that they had in previous games. Also many skills unigue to each charcter (sorta like IX or IV) and make each skill useful as opposed to only to be used if your bored skills.

Also having weather in battles. That way if it's say raining, then water attacks are powered up, fire is down and lightning get's a boost as well, and such. That way weather can effect your strategy for battles. And day and night systems could add to the game, such as you have to wait until night to infiltrate a enemy base. Or some events only happen at night time.