You know how there is two save slots in the Thunder Plains? Well! I discovered a veryy convenient way to do the 200 consectutive lighting strikes to get Lulu's Venus Sigil:

[By the save spheres]
Do however many strikes you want, preferably i stop at 20, cause 20-50 is usually when i mess up, after you do so many, like 10-20 or whatever you prefer, and save it BEFORE you get hit again with lighting! Then if you get hit by the lighting again, just restart the game [hold L1 L2 R1 R2 start & select] and start from whatever number you were on. it goes by MUCH faster. :)

I really hope I helped!!!:)