The set will feature Zygarde, as you can see on the temporary booster pack image to the right. There will be 94 cards in the set, excluding the 5,000 secret rares.
The set is touted as the “second set” of the TCG’s “season two,” meaning the second set of the Ultra Sun and Ultra Moon block. This is also why starting with SM5, Japanese cards now have a “B” at the bottom of each card rather than an “A” like previous SM sets — they’re part of the second “B” block.
As I guessed in one of my earlier stories, it’s possible the Sinnoh advertising is because each new set of this B block will feature a Pokemon region. SM5 is obviously Gen IV Sinnoh and it’s possible SM6 will be Gen VI Kalos. If the “set theme” turns out to be true, it could be because USUM features each game’s boss and that’s they’re excuse to revisit each region.
(Or it’s all advertising that will lead up to a Switch game featuring all the regions. :x)
Also announced for a February 16th release in Japan are a new “Ultra Sun” and “Ultra Moon Deck Building Box.” Each of the boxes will come with ten booster packs of either SM5 Ultra Sun or Ultra Moon, three SM5+ packs, 46 Trainer cards (26 unique), four Special Energy (two unique), 108 Basic Energy (9 x 12), and a deck box. Each package will retail for 3,500 yen, or about $31.
February 16th will also see the release of a new set of sleeves featuring Pikachu and a new set of sleeves featuring Lillie, Mallow, and Lana together. Naoki Saito, the illustrator of full art Lillie from SM4+, will be drawing the artwork for the human sleeves.