Although the set’s name implies it will have a red-colored theme, the Elite Trainer Box will actually be blue and feature Silvally. Perhaps this is because Silvally is the “good” defending against the Ultra Beasts.
The set’s mini album will feature Guzzlord and Silvally. It’ll come with one Crimson Invasion booster pack.
So far the only information we know about the English set is from this news story. On the Japanese side, only Feebas has been revealed from the set, although the set logo and card number were hidden from the card’s image. We’re not supposed to know the set exists yet.