It looks like we’ll be skipping over Japan’s reprint set, CP4 Premium Champion Set (at least for now).
The set will feature shiny M Gardevoir-EX, Volcanion-EX, Xerneas BREAK, and Yveltal BREAK.
The set’s description says “Long years of stability come to an end when Shiny Mega Gardevoir-EX lays siege to the mighty Gear Palace with a host of greedy forces. The Mythical Steam Pokemon Volcanion must wield the dual powers of Fire and Water to stop them!” This seems to be giving us some plot hints about the Volcanion and Magearna movie, such as shiny Mega Gardevoir being a traitor (or perhaps being used by Jarvis, the bad guy).
In terms of the Japanese set, all we know so far is that it’ll have 108 cards, it’ll feature Pokemon from the Volcanion and Magearna film, and there will be a new game mechanic. The set will be released on June 17th in Japan ahead of July’s Volcanion and the Mechanical Magearna film.
The English set will also release the usual array of supplementary products, such as a Volcanion Elite Trainer Box.