Pokédex

The Pokédex is a handheld electronic Pokémon encyclopedia. It is first given by Professor Oak at Pallet Town to the player. It is one of the main objectives of the game to complete all entries of the Pokédex.

Use
To access the Pokédex, open the 'Menu' tab seen on the left of the screen. Click the uppermost selection in blue text called 'Pokédex' to open it. There are three stages of discovery in the Pokédex: NOTE: Only Pokémon that have been owned by you (by means of capturing, roulette, trade or mystery gift) are counted in the Trainer Card's Pokédex statistic.
 * 1) Unknown - The entry's name is '?????'. There is no information.
 * 2) Discovered - The entry's name is registered. There is limited information.
 * 3) Captured - The entry's name is registered and there is a Pokéball beside its number.

Accolades
There are currently three ranks acquirable from Pokédex entries. You also encounter Professor Oak again in Saffron City's PokéCenter. If you talk to him with 300+ Pokédex entries, he will give you a particular Pokémon. You need a spare space in your party to receive it.
 * Pokémon Trainer - 100+ Pokédex Entries
 * Pokémon Expert - 250+ Pokédex Entries
 * Pokémon Master - 450+ Pokédex Entries

Interface
The Pokédex's interface is simple and easy to use. There are two main components of the interface. To the left is the scrollbar with the entire list of Pokémon entries. A search filter above makes it easier to find a specific entry. To the right is information regarding the selected entry. When complete, it displays its Name, Species, Height, Weight, Type, Description and National Number.

Pokédex
Note: Most Pokemon are not in-game yet.

In pokemon games there in an upgraded Pokedex that if you catch all in that route you can find

see everything in that route

Generation VII
There are currently more Pokemon to add.