Got asked about this on Discord so let me copy my answer over to forum posts in case someone else is looking for the same stuff.
In 2018 TPC printed several sample decks and gave them out in order to promote TCG play. The sample decks consists of mini cards which are approximately 60% in size comparing to regular TCG cards.
Different mini decks are released through various channels:
- The first deck was given to visitors of World Hobby Fair 2018.
- Two more decks were given out for free in local shops.
- All other decks are released with various issues of Corocoro Ichiban and its bonus issue Pokémon Fan magazines. For example Pokémon Fan issue #58 includes the following deck:
From what I know these Corocoro Ichiban issues also have decks:
- October 2018 issue - Zeraora deck
- January 2019 issue - Lightning Master deck
- October 2019 issue - Mewtwo & Mew GX deck
I can’t really recall exactly if other issues also had decks with them, but in case anyone want to find them all here’s how:
- Go to the publisher’s book search page:
a. Corocoro Ichiban
b. Pokémon Fan only - Click on every issue - IIRC the decks are released mostly with issues published between 2018 and 2019
- Translate the page and look for keywords “mini” (ミニ) and “deck” (デッキ) (don’t look for “mini deck” as a whole word as some of the deck names have the words separated )
- Mark the issue number if you got a hit
Oh and BTW, PSA grades them if they’re able to tell which deck the card was from and that the cards are hand-torn (not cut) off the sheet. No joke.