Very rare item
It appears that several Pokemon TCG illustrators (and possibly Creatures employees) have recieved a special commemorative gift from Creatures Inc. This 25th Anniversary themed wooden box includes a Pokemon Card Game pouch and a special never seen before Creatures Deck with Corporate History shows exclusive 25th Anniversary cards.
These cards are not seen in our Celebrations or the Asian 25th Anniversary Collection set. Creatures mentions on the letter inside the box, that it's a Pokémon card-shaped company history.
On the back of these cards is corporate history shown of the past 25 years. All cards have glossy holofoil treatment and the majority of these cards except for a handful, are exclusive to this exclusive deck. Creatures mentioned you can play this as a 30-card deck, there are also 32 deck sleeves included with the original card back design and 1 How to Play guide card.
There is also a never seen before hand drawn / minimalistic version of Chansey based off the Base Set version. It mentions on the back of the card that this is a test card by Kouichi Ooyama. The test card has a different effect than how it was released later in the Base set. It does 50 instead of 80 damage to itself.
Chansey Test Card Image by LeeHyunJung
This might be just as extremely rare as the Pokemon Card Game 20th Anniversary Deck Box that sold on auction for $11,200 last year, that was also only issued by Creatures Inc. to Pokémon TCG illustrators, and celebrities Minami Takahashi and Shoko Nakagawa at the time.
There is also a instagram story video showcasing the contents inside by illustrator Shibuzoh. (link here). We tried to capture screenshots.
Update: History Gate Stadium card has been revealed from this box. It says:
All HP and damage from moves written on cards released between 1996 and 2000 are multiplied by 2 in your field.
Also added 2 images that showcase all decks in the 30-card deck together.
Update 05-01-2022: Added better pictures of the 3 special cards (History Gate, Poké Ball & Switch) in the 25th Anniversary Creatures Deck. These 3 cards are all numbered 011/008. Also, the QR code on the card back leads to an interview page:
Images via pokexperto.net.