I've heard that there is a glitch with this nightmare of a sidequest. I'm not sure of the exact details but I think its something to do with getting hit 5 times on the north side then getting hit once on the south side then something in between before opening the chest. Anyone know about this?:mog:

Edit - I've Google this and come up with the following. I'm playing VIII again at the moment but if anyone tries this can they let me know what happens.

To dodge 200 lightning bolts easily, use the airship to get to the Thunder Plains, and go to the northern part. Dodge enough lightning bolts consecutively to make the chest appear but do not open it yet. The amount of times needed to dodge for the chest to appear will be different for almost everyone attempting this trick. Stay close to the exit so that you can leave quickly before lightning strikes again. After dodging, go back past the treasure chest and enter the southern part, then immediately leave and go back up past the chest to the northern part and get hit twice by lightning. Go back to the chest and open it. It should say that you dodged 200 consecutive lightning bolts or more. Make sure to stay close to the exit when dodging or getting hit by lightning so that you can leave immediately before lightning strikes again.