Hey all,
this subject is really close to my heart, so bear with me for a lengthy and picture-heavy thread where I will try to convey my bold claim of why I think these are the “best” non-TCG items.
When I hit up the e4 search engine, there wasn’t even one single fitting result. So I guess it’s fair to assume that the majority here isn’t aware of these books.
Pokemon Tales, or ポケモンえほん in Japanese, are a series of picture books published by Shogakukan, Inc. from 1997 - 2003 with a total release of 61 volumes, seperated into 4 discrete series. 34 of these volumes were also translated in English. You can look up the Bulbapedia page for more details.
As they were primarily targeted to small children, the books are typically made out of thick cardboard and have each merely 18 illustrated pages with a little short story. They typically focus on the interactions between Pokemon and their adventures, not on fighting or human trainers.
Now the most interesting part to me are the illustrators of these books, because many of them are absolute staples in the TCG.
Arita, Himeno, Komiya, Tanaka, Baba, Kimura, Ooyama, Kizuki, Morii, Aoki, Itoh, Kusube, Harada - heck, there’s even one from our beloved Keiji Kinebuchi. Many of them even illustrated multiple books.
I know that for many of us, one of our favorite qualities of a TCG artwork is when it is able to tell a story - so then what could be better than a literal story solely consisting of exclusive artwork by our dearest artists that can’t be seen anywhere else and straight from the golden age?
I was able to get hold of a substantial collection from Mercari Japan and am now in the possession of 45/61 books. I want to share some of my personal favorites and examples from artists that I know have a solid fanbase on e4. I’ll always show the cover and first double page. If you want to view the whole book, just click on “Spoiler” 
Pokemon Tales #1: Charmander Sees a Ghost (Kagemaru Himeno), June 1997
SPOILER: Click to show
↑ btw., on the binding of the very last page of each book, there’s always one Pokemon that’s “hidden” somewhere in the story (in this case it’s Mew) and it’s your fun little side-quest to find it
PT #6: Onix Underground (Benimaru Itoh), July 1997 ← this one has some wild 90s CGI.
SPOILER: Click to show
PT #8: Transforming Metamon (Sumiyoshi Kizuki), July 1997
SPOILER: Click to show
PT #10: Let Me Borrow Your Leek, Kamonegi-kun (Yukiko Baba), July 1997
SPOILER: Click to show
PT #12: Sihorn and the Planet’s Navel (Mitsuhiro Arita), August 1997 ← just a Ryhorn casually piercing through the entire globe
SPOILER: Click to show
PT #16: Ready, Set, Dodo! (Tomokazu Komiya), October 1997 ← one of my absolute favorites. As “Komiya” as it gets!
SPOILER: Click to show
PT # 33: Little Ghost (Aya Kusube), June 1998 ← There’s a wonderful YT video that reads the story in English. This exact video is actually how I first found these books.
SPOILER: Click to show
PT #34: Magnemite’s Mission (Keiji Kinebuchi), June 1998 ← wild CGI, even wilder story!
SPOILER: Click to show
PT #36:Let’s Make Pizza, Wanriky! (Yuka Morii), July 1998
SPOILER: Click to show
Phew. That’s a lot of pics.
The elephant in the room is obviously that i can’t read Japanese. The artworks do most of the talking, tho.
If you by any chance have some of these books and want to help me to complete my collection, I invite you to check out my Pokemon Tales Checklist, where you can see what I have and what I still need.
Lastly, for the love of god, please don’t quote the entire post. Otherwise this thread will become a completely unreadable mess, haha 
Really hope this gives you a little insight in these wonderful books and maybe even motivates you to get a volume from your favorite illustrator or one that features your favorite Pokemon.
Cheers!
