Cheap, clever - it's your call what you call it. The key is to have Overdrive -> AP on any weapon and preferably as many boosts as you can (Double, Trip Overdrive, Double, Trip AP). Then select Loner as your Overdrive mode. Once in battle, have Tidus cast haste on the character you wish to level, kill all enemies except for one, cast slow on it, then have all your other characters leave. Now simply defend... every turn...
If done correctly, each move that character takes should charge his Overdrive bar, thus boosting his AP. I did this with Tidus a few minutes ago to try it out. Probably smashed the triangle button for about 5 minutes or so... he went up 30 levels.
This will also worth with various other overdrive modes. You could do your entire team with the Sufferer Overdrive mode but I'm not really sure how to inflict status ailments on yourself without having them be a pain in the ass or only temporary. I recommend against Ally since it's so fucking slow.
If done correctly, each move that character takes should charge his Overdrive bar, thus boosting his AP. I did this with Tidus a few minutes ago to try it out. Probably smashed the triangle button for about 5 minutes or so... he went up 30 levels.
This will also worth with various other overdrive modes. You could do your entire team with the Sufferer Overdrive mode but I'm not really sure how to inflict status ailments on yourself without having them be a pain in the ass or only temporary. I recommend against Ally since it's so fucking slow.