- The wording of Jamming Net is now as follows, "The attacks of the Pokémon this card is attached to do 20 less damage to each of the opponent's Pokémon (before applying Weakness and Resistance). (Don't apply Weakness and Resistance for Benched Pokémon.)" This tool should only impact the Pokémon belonging to the opponent of the attacking Pokémon.
Source:
TPCi Announcement (2014-11-18), TPCi Rules Team (2014-11-20)