I rarely used Aeons - except as sacrificial lambs...but I have the US version (still waiting to see Anima's OD in X: International)
...so instead I just spam Quick hit - or, if I don't have it yet, I rotate all my characters in, defending with each to make sure they gain Sp. Lvls - then rotate back in whoever's going to finish them off quickly - usually a combination of Tidus' sword, Lu's Blk magic, and Auron's mighty blade/Wakka's blitzball attacks. ^ ^
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Fight, if there is something to fight for.
Never give in, or give up - but ALWAYS give.
Choose your battles wisely.
You only get one shot at life. Follow your heart.