Variable-power, or multi-hit moves, usually calculate their Max Move power based on the best-case scenario. For Electro Ball they don't go quite so far, as its best case is a 150 power move which would also translate to 150 max power on the standard schedule, but they do assume a somewhat favorable case of being 2-3 times as fast as the opponent as the default for its single Max calculation to be based on, as that normally gives 80 power and translates to a Max Move power of 130 in all cases.
