What if there were a skill that allowed you to copy the last skill you used?
It's something that hasn't been done yet, and while it would be very USEFUL for certain teams, I think it's manageable enough to not be that overpowered. (You could also have an "enemy skill" one that copies what an enemy used, but I think that would be less useful).
Uses:
Extra full-board changes
Extra hastes
Extra lasers
Extra Myr (next turn), etc
Just more flexibility, because you can technically bring multiple of these things above without ACTUALLY bringing more of these things

Limitations:
RNG, but could be negated by forcing other actives (IE, you want to copy a full board change or whatever, and the boss hits and you have to heal instead, so then it would copy the heal)
Less useful for heroes, archangels, AKagu, Akechi, etc
Delays have long effect periods so you'll have to not use skills till they wear off if you want to copy them

I dunno, thoughts?
(Full disclosure, been playing my first Pokemon since the original games, so Ditto, there's that).