From Bulbapedia, the community-driven Pokémon encyclopedia.
Pokémon language is the medium by which Pokémon communicate with each other and with humans in the games and the anime. This may include communicating through the Pokémon's cry, through the human language, through body language, or through some other means of communicating, such as telepathy or by possessing a human or a fellow Pokémon that is able to speak.
- Main article: Cry
In the games
For a vast majority of Pokémon in the games, the only sound they are capable of making, is their cry.
When a Pokémon is brought into battle, regardless of whether it is being encountered in the wild or summoned by a Pokémon Trainer, an audio cry will be heard. Pokémon also use their cry when using certain sound-based moves, such as Growl. Another way to hear the cry of a Pokémon is by looking that Pokémon up in the Pokédex.
Every species of Pokémon has its own cry, while there are some who seems to have identical cries, for example Charizard's and Rhyhorn's.
In the Pokémon Black Version 2 and Pokémon White Version 2 Animated Trailer and Pokémon Origins, Pokémon make animal-like sounds that differ from the game's cries.
In the anime
Typically, Pokémon will have a cry that is identical to their own species' name. For example, a Charmander will only be able to say the actual word "Charmander," in part or in whole.
Despite apparently speaking only their own species' name, Pokémon seems to be able to communicate with each other without issue. In Island of the Giant Pokémon, there are subtitles for what the Pokémon are saying, and evidently they could understand each other perfectly. Communication between Pokémon has become especially crucial in Double Battles, Triple Battles, and Tag Battles. An example of this can be seen from the conversation between Ash's Pikachu and Dawn's Piplup in Arceus and the Jewel of Life, when communication between those two Pokémon was vital in saving their Trainers.
While it was originally assumed that all cries by Pokémon were the same, dedicated fans have been able to find what appear to be patterns, such as Ash's Pikachu saying "Piiika-Chuuuuuuuu" when using Thunderbolt or "Pika-Pikachu" when referring to himself, Pika-Pi when referring to Ash. Dawn's Piplup also shows patterns, such as "Piplup-lup-lup" when using BubbleBeam, or "Pipluurrrp" when using Whirlpool, with the 'lup' becoming distinctly watery.
- Main article: Talking Pokémon
In the games
There are a few Pokémon that are able to speak the human language, such as Copycat's Doduo in FireRed and LeafGreen Versions, and a Murkrow who appeared in the Team Rocket HQ, in the Generation II games and their Generation IV remakes. A Zoroark in Lostlorn Forest has a fluent conversation with the player whilst disguised as a male Backpacker, showing that some Pokémon are capable of holding conversations in the human language.
It is unknown to what extent Pokémon understand the human language. Lapras's Pokédex entry cites its ability to comprehend the human language, possibly implying that not all Pokémon can fully understand the human language. It seems that Pokémon can generally understand the human language at least enough to comprehend their Trainer's commands, as demonstrated by Lance telling his Dragonite to use Hyper Beam on a Team Rocket Grunt in the Generation II games and their remakes and various Trainers directly commanding their Pokémon in the Pokémon Black Version 2 and Pokémon White Version 2 Animated Trailer.
In the anime
Unlike the games, there are only a few Pokémon that can have fluent conversations with humans. The most well-known talking Pokémon is Team Rocket's Meowth, who relentlessly learned human language to impress his love interest, Meowzie. This has made him a common interpreter between the humans and Pokémon in the anime.
Other major Pokémon that could fluently hold conversations with humans include the Slowking in The Power of One, a Snover in Pikachu's Ice Adventure, and a Gastly in The Ghost of Maiden's Peak.
When Pokémon are outside of their Poké Balls, they have a distinct body language that can sometimes be their primary way of communicating with humans.
In the games
In Pokémon Yellow Version, the player's starting Pikachu will be outside of its Poké Ball and follows the player around, much like Ash's Pikachu does in the anime. If the player turns around and talks to the Pikachu, an image will appear on the screen above Pikachu, showing its expression, which changes depending on its mood. For example, when the player starts the game, Pikachu will be unhappy to be stuck with the player, but as its friendship increases throughout the game, its expressions will become more positive.
In HeartGold and SoulSilver Versions, the Trainer's first Pokémon in the party, will follow the Trainer around for a majority of the game. However, unlike in Yellow Version, if the Trainer turns around to talk to the Pokémon, an image will not show up. Rather, the text at the bottom of the screen will give a description of what the Pokémon is doing.
In the anime
Ash's Pikachu is the most notable Pokémon for using dramatic body language to communicate. Several Pokémon appear to use motions and body language, essentially playing a game of charades with their Trainers. This has led to many humorous moments throughout the anime.
Other means of communication
Many Pokémon, mainly Psychic-types, interact with humans via telepathy. For instance, in Do I Hear a Ralts?, a Ralts telepathically called Max for help; however, it may have been crying out to anyone and Max happened to be the only one who heard it. This is not to be confused with the Ability, Telepathy.
Ash and Pikachu communicate through their partnership
Latias communicates as Bianca
Most talking Pokémon speak telepathically, such as the Zorua in Zoroark: Master of Illusions. Many legendary Pokémon are able to do this as well (for example, Lugia in The Power of One).
It seems that an experienced or empathic Trainer may be able to communicate quite fluently with their Pokémon, if only intuitively. In Saving the World From Ruins!, Ash understood that Pikachu wanted to use Thunderbolt to help Riley's Lucario, for instance.
Through someone else
Some Pokémon have been able to speak telepathically through a person or another Pokémon. In A Shipful of Shivers, a Gastly and Haunter speak through Meowth.
The Latias in Pokémon Heroes was able to bend light in order to make herself appear as Bianca, a girl whom she had befriended and was able to communicate with the human language as her.
In Just Waiting On a Friend, a Ninetales created an illusive girl named Lokoko through whom it spoke.