"If you need instructions on how to get throught the hotels, check out the enclosed instruction book!"
~Mario from "Hotel Mario"
Legends. It allows the user to see brief info about the selected enemy, such as attacks, special forms, required tactics and weaknessess. Inside the book, Mario found the Power Glove, which allowed him to defeat Iron Knuckle.
In CD-I Pokémon Tournament, we find out that Ganon has his own version of the book called The Evil Enclosed Instruction Book, but he can only use it once he obtains The Triforce of Power. The book proved to be useless during his fight with Bowser, because the info about King Koopa was censored by SOPA (as well as info about Link Nukem, which would reveal his only weakness). After the fight, in the hospital, Ganon ordered his minions to punish the SOPA corporation ruled by Walleo and Waweegee by sending them a Morshu Bomb and completely destroying the planet they were both living on.