Usually, decklists are checked at the beginning of most large-scale tournaments so errors like this don't happen, but if something gets through, this is what would happen:
~If the deck has more than 60 cards, cards are removed until it contains at least 60, in accordance with the judge's penalty.
~If the deck has less than 60 cards, the remaining slots are filled with basic Energy of the player's choice, in accordance with the judge's penalty.