Are there any good ways to stand extreme super-leveling?

[Zeromus_X]

Well, you'll certainly be busy for quite some time then. I believe in the GBA/PS versions the HP and MP cap at 9999 and 999 respectively.

I've always seen powerleveling as a waste of time, unless there's an optional superboss that requires your characters to be maximized (which, there never usually is).

In this game, the final dungeon itself is a perfectly good reason to power-level.
I mean, this Malboro inflicts you with like every status ailment in the whole game from one normal physical attack...?
And that's on the first floor; you've got lots of more floors to go, and of course they prove even deadlier.

If you're extremely cautious about using magic, you'll still need over 300 MP in order to cure everything on your way through, at least if you, like me, tend to have each character focus on certain abilities = one White Wizard.

But that Turbo Button thing is actually a good idea.

Many late-game enemies are going to be taking out a good fraction of your HP regardless of how many nines are contained in it; you'd be much better off prioritizing the evasion stat so that you can just dodge attacks altogether.

I'm not arguing that the final dungeon in FFII isn't extremely challenging, but there are always better things you can do with improving your strategies and such than just mindlessly power-leveling. This is true of every RPG.

As for my own maximization method, on my first GBA playthrough, I made use of the Swap trick to power level my characters' HP and MP. It didn't take terribly long, either, although it might take a bit longer in the NES version. It'd probably be faster with whatever method you're using and your emulator's fast-forward button.