In case someone looked it up on Bulbapedia and was going to ping me for it (and yes, someone already did lol ): all information regarding this card came from the official card database:
And for Japanese and Korean promos, TPC and KR always specify their sources on the card entry pages, which for this card says:
스티커 컬러링 포켓몬스터 1,2 부록 (Sticker Coloring Pokemon 1,2 Appendix)
However as we have experienced before, finding a card on the official site doesn’t mean it was officially released… so I wouldn’t be able to provide further help here. (One thing you might want to try is to call officials directly and ask them what’s with the card entry - I tried it with TPC when investigating on some other cards but they never responded, perhaps PK would be more responsive.)