actually, the best thing for lightning dodging is doing it at the right time:o

ideally, all the celestial weapon sidequests should be done between 5-9:00 PM (that's when I did rikku, kimarhi, and lulu's, at least, three rather intense/annoying ones:P) This is a time of the day when teenagers like ourselves are wide awake still and able to think. Sometimes you don't think about doing sidequests until 2:00am, but you've lost most of your coordination by thenxD

FOr lightning dodging specifically, try doing it on a night when there's a REAL thunderstorm outsidexD and having someone to talk to and yell at and plead with not to turn the tv channel.