The second set of Stacking Tins will feature the Fighting, Fire, and Darkness-types!
They will release on October 28th for $12.99. Each tin will come with three booster packs and a coin. As implied by the name, the tins are designed to stack on top of each other.
The first set of Stacking Tins were released in February. They featured Decidueye, Wishiwashi, and Electivire.
It seems these tins will release twice a year. Presumably the next set will feature Psychic, Dragon, and Metal Pokemon.