Beginning on May 22nd and while supplies last, customers that purchase five “Detective Pikachu” expansion packs via Pokémon Center Online will receive one promo Detective Pikachu card as a bonus, while customers that purchase a “Detective Pikachu” booster box will receive four Detective Pikachu promo cards.
Aside from being cute as a button, the Detective Pikachu promo card features an ability that translates as “Trudgingly Go Home”, which allows you to swap an active Detective Pikachu for another Pokémon waiting in your Bench area.
The same 5 booster pack promotion will run at Pokémon Center and Pokémon Store retail locations throughout Japan later once they re-open.