Easy Winning
on the sphere grid you need to keep giving the charachters more hp and on a weapon for each make sure that there is "break hp limit" on it. Once you do this your hp will be able to go all the way to 99999. During the fight make sure to use auto-life on all. Have Rikku use her overdrive and mix two door to tomorrows (will create trio of 9999) Then use tidus' overdrive Blitz ace. When rikku's overdrive guage is filled mix a gamblers spirit and a door to tomorrow, or two supreme gems, or two dark matters. (sunburst) If you are still stuck after doing all this got to www.ffspirit.net they have answers too.