Strongest: Grand Summon (Yuna)
Can you say Overkill?
I usually have my Aeons in Overdrive to begin with, so it was a bit like cheating...but it worked. Grand Summon Bahamut, Mega Flare to kill the first form of Braska's Final Aeon, then Mega Flare again and bam!, down for the count. Piece of cake. (Bahamut in general was Overkill, heh.)
Coolest: Tornado (Auron)
The many uses of sake...lol. First time I used it I was so amused I promptly had to use it three more times just for the entertainment factor, never mind the Overkill.
I never did get around to using all the Overdrives though...maybe I'll go back and get them someday.
~DragonHeart~