I remember in 2008 I finished High School and I won a PS3 at a drawing, at this time the PS3 had nothing I wanted so I traded it in to Game Crazy and got a PS2, Kingdom hearts, Tales of Abyss, and Final fantasy 10 I spent almost my whole summer playing Final Fantasy 10.
if you use riku with auto heal on one of her targes he will target her most of the time be sure to have holy water for it to work, I beat him without using aeons by pure luck and Kimahri
And no getting Tidus's legendary weapon is NOT essential to winning the game. I've played this religiously going many different ways and angles and trust me you don't need all the celestal weapons to beat the game!!!