Oh, thats easy but confusing. You see, voltage means the amount of stars the judges give you. For example, my espeon uses psychic and the judge gives 3 stars. Then, when I use morning sun/moonlight, the judge will have 6 stars. If I use tackle and the judge has 2 stars, then when I use moonlught/morning sun, the judge rates the move 2 stars and will have 4 stars. A bit confusing, but try doing Pokemon contests alot and it will make sense