Large-sized, Gold Mirror Holofoil, Black-backed Coin featuring Pikachu released within later shipments of the XY Trainer Kit: Pikachu Libre & Suicune October 5, 2016; later released within the Sun & Moon Single Pack Blisters February 3, 2017 and again as a possible coin within the Jirachi-GX Collection November 1, 2020

Thanks for looking!