Well, I know there is a bunch of way to get mass amounts of AP, and most of them better than the one I figured out but for people who are willing to try it out will find it very useful.
First, you will need (about)99 doors to tomorrow. Customize everyone�s weapon with the ability Overdrive -> AP. I didn�t understand what this meant when I first saw it so let me explain. Overdrive -> AP means if you get 1 hp takin off because you have been attacked, then you get 1 AP. So getting lots of damage gives lots of AP. The drawback is that your overdrive gauge doesn�t fill up.
To get the 99 doors to tomorrows, you have to capture a certain number of fiends for the arena. Trust me, it�s worth the time. After customizing your weapons (any weapon with 1 or more slots) make sure you can fight the boss Cactuar King in the monster arena. Buy lots of phoenix downs too. Now just have the characters you want to gain AP out battling the cactuar. He will do 2 attacks. 10,000 needles and 99,999 needles. Let him attack then use a phoenix down. Just keep doing this but DONT attack him; if you do, he will run away after a few turns. Now you can just keep doing this as long as you like and each time he hits you, you get 99,999 or 10,000 AP. There is also ways you triple your AP for a fight, but figure out how to do that yourself.
If you have other ways, that dont take 3 hours to do, then please post.
