This is a rather interesting card from the upcoming Primal Clash set. Negating weakness is nice, but is it really worth taking up the spot of a Tool? Using this, a Pokemon will no longer have access to a Muscle Band or a Spirit Link, in the case of something like M-Manectric-EX, which has a potentially dangerous Fighting weakness. Manectric is one of the Pokemon that I'd be most inclined to attach Weakness Policy to, but I wouldn't want to give up my turn when I need to Mega Evolve. I feel like in so many situations this card's benefits aren't worth its drawbacks.
However, I think it can have a niche role in a small number of Decks. Trevenant XY has limited playability due to its Dark weakness and the loss of its buddy Accelgor to paralyze and poison. Being weak to Yveltal in this format is no laughing matter. While Yveltal is no longer "the deck to beat," it's still a powerful and credible threat in the metagame, and sees its fair share of play. Trevenant XY is one of the few cards I can think of that could make wonderful use of Weakness policy, perhaps in conjuction with Gengar-EX, which also has seen limited success. Keldeo's Rush In + Float Stone combo has already been used in the past to assist with Trevenant's hefty retreat cost (and Gothitelle before that) and as a means of conserving Float Stones in case Trevenant is KOed. With Gengar-EX's Dark Corridor, this could make for a lock that's a little harder to break. Dragalge is optional. Wobuffet PHF is another good candidate for Weakness Policy to deal with opposing Mewtwo-EX, and would work in a simialr sort of deck. Still, this is complex idea and it's very much a niche role, so don't expect Weakness policy to have a huge impact. It does however, allow for some creativity that the metagame until this point hasn't allowed. Your thoughts?