How? How do we not have a book Pokemon yet? But rather than just an inanimate book, I propose a Dragon/Bug-type Pokemon. It’s a book wyrm. Heck, we can even call it Bookwyrm. It’s a very, very small dragon, small enough to look like a bug, and it loves books. It lives in books, it reads books, and carries an enormous tome around everywhere to use both as a shield and to read, so it will keep growing stronger.
In addition to Bug and Dragon moves, Bookwyrm would make use of its book-shield for abilities like Light Screen and Reflect, while I think a unique ability could be added to allow it to increase its Special Attack at the end of each turn it didn’t use an offensive move (effectively, any turn it had time to read!). In an ideal universe, at a very high level (like, 60+ somewhere) the Bookwyrm would merge with its tome to evolve into a monstrous literary dragon that used all the knowledge from all the books it had ever read to become deadly powerful and rare.