A Pokédex is a device that can be used to check out all of the 649 Pokemon in detail in the Pokémon games and in the anime. In the animated series, it is presented to Ash when he got Pikachu in the first episode by Professor Oak. Later seasons included upgradeable versions of the device and in season 10, Dawn received her very own by Professor Rowan after she got Piplup.
The Generation I Kanto Pokédex of Pokémon Red/Blue and Pokémon Yellow: Special Pikachu Edition was the first model introduced, and is iconic of the original popularity of Pokémon. The in-game sprite of the Pokédex resembled a book, suggesting that the original envisioning of it was that of an actual encyclopedia, not an electronic device.
The Generation II Johto Pokédex of Pokémon Gold/Silver and Pokémon Crystal adds the ability to view a Pokémon's footprint. It resembles a Game Boy Color.
The Generation III Hoenn Pokédex of Pokémon Ruby/Sapphire and Pokémon Emerald did not add any major features, though there were menu changes. It resembles a Game Boy Advance.
The Generation III remakes of Pokémon Red/Blue, Pokémon FireRed/LeafGreen, introduced a redesigned Kanto Pokédex. It was the first Pokédex to display a Pokémon's type and menu sprite in its entry. It resembles a Game Boy Advance SP.
The Generation IV Sinnoh Pokédex of Pokémon Diamond/Pearl and Pokémon Platinum added many new features, such as displaying gender and form differences and viewing entries in different languages if the player received a Pokémon from a foreign player. It resembles a Nintendo DS Lite.
The Platinum version has a slightly different color scheme, reversing the blacks and grays on either side of the screens and on the "D-pad".
The Generation IV remakes of Pokémon Gold/Silver/Crystal, Pokémon HeartGold/SoulSilver, introduced a redesigned Johto Pokédex. It has most of the features of the Sinnoh Pokédex, though much of the interface is different. It resembles a Nintendo DSi. It has the standard orange-red color scheme if the player character is a boy and a white/pink color scheme if the player character is a girl.
The Generation V Unova Pokédex of Pokémon Black/White and Pokémon Black/White Version 2 shows the seasons in which a Pokémon can be found, and form differences now also show Shiny Pokémon. The player can download extra skins for the Pokédex through the Pokémon Global Link. The Unova Pokédex resembles an iPod. Boy player characters get a black/orange model and girl player characters get a gray/pink model.
In Pokémon Black/White Version 2, the Pokédex can be upgraded wih Habitat Mode, which shows which Pokémon the player has already seen in an area, and marks with stamps on the map display depending on if the player has seen or caught all the Pokémon in an area, allowing for easy management. The Black 2/White 2 Unova Pokédex is physically identical to the previous model, though it has a new interface.
The Generation VI Kalos Pokédex of Pokémon X/Y is a flat device with two main sections that pull out to reveal a center screen that uses touch controls. Because of the large size of the Kalos region, the Kalos Pokédex is split into three categories: Central Kalos, Coastal Kalos, and Mountain Kalos. The design resembles a modern smartphone.
In the Pokémon Adventures manga, only few very select people are allowed to have Pokédexes; in this case, the main characters. Each protagonist starts with their corresponding games' Pokédex, upgrading to the newer model in story arcs based around remake games and losing their original Pokédex through some process, such as Blue's first Pokédex being destroyed and Red giving his first Pokédex to Yellow.