From Bulbapedia, the community-driven Pokémon encyclopedia.
A Pokédex (Japanese: ポケモン図鑑 illustrated Pokémon encyclopedia, sometimes also rendered as ポケモンずかん illustrated Pokémon encyclopedia) is an invaluable tool to a trainer in the Pokémon world. It gives information about all Pokémon in the world that are contained in its database. In the games, it lists the number of Pokémon seen and caught. In the anime, simply pointing it at a target Pokémon will give someone the Pokédex entry for that Pokémon. Pokédexes in both the games and anime are not given to all trainers, but given to trainers of exceptional potential and skill. In both the games and the anime, Ash and Gary both received their Pokédexes from Prof. Oak, although through different circumstances. Ash was notorious for using his Pokédex in situations where he had no idea what was going on, and was just as notorious for always being behind Gary in Pokédex entries.
Pokédex entries are typically only two- or three-sentence bits of information about the Pokémon referred to. In some events it gives background information on the habitat or activities of this Pokémon in the wild; at other times it gives other bits of information on the Pokémon's history or anatomy. A typical entry would be one of Bulbasaur, which states:
"A strange seed was planted on its back at birth. The plant sprouts and grows with this Pokémon. "
To date, there have been five different versions of the Pokédex.
Kanto (Generation I)
The first version of the Pokédex recorded data on the first 151 Pokémon, focusing on Pokémon mostly native to Kanto. It listed them in number sequence, and it recorded data on height, weight, number, species, cry, and nesting area. In Pokémon Yellow, the option to print Pokédex entries using the Gameboy Printer was added.
In the anime, the Pokédex model's program is referred to as Dexter, as well as the programs for most models of the Pokédex. When Misty got Togepi, Professor Oak updated this model with new software that included data on a handful of Johto Pokémon. Its Japanese voice actor is 三木眞一郎 Shinichiro Miki, its English voice actor is Eric Stuart and its Brazilian voice actor is Wellington Lima.
The second Pokédex had many improvements. Data on 251 species of Pokémon could be recorded. Pokémon could be listed in the Kanto (or National) order, a new order focusing on Johto, or by alpabetical organization. A new search option allowed users to find specific Pokémon by type. Entries were expanded to include a Pokémon's footprint (if it had feet). Also, the design of this Pokédex is markedly similar to that of Nintedo's GameBoy, GameBoy Pocket, and GameBoy Color.
In the anime, its Japanese voice actor is 三木眞一郎 Shinichiro Miki, its English voice actor is Eric Stuart and its Brazilian voice actor is a computer-made voice.
The third PokéDex could record data on 202 species of Pokémon native to the Hoenn region. An upgrade called the National Dex was unlocked if a trade with Kanto was made, or if the Elite Four were defeated in Pokémon Emerald, which would allow 386 species to be recorded. Pokémon could also be listed by weight and size. The search option was expanded to include the first letter of a name, as well as color of the Pokémon. The most interesting addition was size charts that compared a 10-year old child to inidividual Pokémon in terms of height. This allowed trainers to get a better idea of how large individual Pokémon were, which often conflicted with depictions in the anime. The print option was removed, however, as no Game Boy Printer was made for the Game Boy Advance.
In the anime, this Pokédex model's program is referred to as Dextette instead of Dexter, and it has a female voice to match. Its Japanese voice actress is 林原めぐみ Megumi Hayashibara, its English voice actress is Rachael Lillis and its Brazilian voice actors are different from AG001 to AG040 until Alex Minei voices it from AG041 onwards and Márcio Marconato voices it from AG093 to AG103, then Wellington Lima voices it AG129 onwards.
Kanto (Generation III)
The fourth PokéDex could record data on 151 species of Pokémon native to the Kanto region. An upgrade called the National Dex was unlocked if the Elite Four were defeated, which would allow 386 species to be recorded. In addition to the improvements made in the Hoenn version, Pokémon were all organized into habitat categories (Grassland, Forest, etc.), where similar Pokémon were typically listed together on the same pages (such as Jynx and Mr. Mime, for instance), and Pokémon who are cross-generation evolutions are also displayed next to each other, such as Onix and Steelix. Nest display was also expanded to include the Sevii Islands.
In anime, this model comes in both red and yellow. Its Japanese voice actor is 三木眞一郎 Shinichiro Miki, its English voice actor is Eric Stuart and its Brazilian voice actor is Wellington Lima.
The fifth Pokédex can naturally record data on the 151 Pokémon native to Sinnoh, with the National Dex upgrade allowing for the 493 Pokémon available to players of Diamond and Pearl to be recorded. Strangely, some of the Pokémon first encountered in Generation IV are not in the Sinnoh dex order, such as the two new evolutions of Eevee. Nest display includes time of day as part of its functions now.
In the anime and Pokémon Special manga, it seems that the color of the Pokédex casing is customisable. Hikari has a pink one, Ash and Berlitz have a red one, Diamond has a blue one, Pearl has an orange one and Shinji has a dark blue one. This Pokédex also has a female voice, by 川上とも子 Tomoko Kawakami.
Its appearance is similar to that of the Nintendo DS, and it may have a touchscreen as well.