Does 10 damage plus 10 more damage for each Energy attached to Ditto but not used to pay for this attack's Energy cost. You can't add more then 20 damage in this way.
Abilities
Form Variation
Poké-Power
Once during your turn (before your attack), you may search your discard pile for a Basic Pokémon (excluding Pokémon-ex and Ditto) and switch it with Ditto. (Any cards attached to Ditto, damage counters, Special Conditions, and effects on it are now on the new Pokémon.) Place Ditto in the discard pile.
Disclaimer: The following data is based on sale history from a third party source. Data is updated about every 5 days. This data does not serve as a value guarantee.