When battling a Electric-based monster in the wild, your most effective fighter will be of the Rock element, as Electric is weak against Rock and Rock is strong against Electric. It is not recommended to fight an electric-based monster with a water-based one as they are weak against each other.
This battle combination will force your attacks to have a 1.5x multiplier attached to them, while incoming attack damage will either be cut in half, or the opposing monster will use a Normal attack if it has one.