A new Build-A-Bear plush has been revealed, and it's Pichu. The promo it will come with, is a Pikachu promo. This promo first was released in the Shining Legends Collector Chest.
Pichu hasn't had a card since HeartGold & SoulSilver, so it makes sense to use Pikachu as a substitute.
You can order this plush (with or without cape) right now. The total price for everything is $61.
Order it here.
Thanks to @SerebiiNet for letting me know.