If you ask any fan of the Pokémon anime to explain how the titular creatures communicate they would undoubtedly point to the well-known self-referential speaking patterns seen in every episode. It's common knowledge that Pokémon only say their own names. Pikachu says, "Pikachu", Bulbasaur says, "Bulbasaur", and a handful of Pokémon can actually speak to humans. This is how it has been since the anime launched in the mid-to-late '90s. But not every corner of the Pokémon universe works this way.
In fact, the original Red, Blue and Green games simply featured chiptune "cries" that each Pokémon would make upon appearing in battle. Obviously the GameBoy was not capable of producing audio effects that sounded like Pokémon saying their own names, but no one is even sure if that was wanted. As Pokémon grew in popularity the notion that Pokémon only spoke their names became a notion that everyone got on board with, mainly because of the anime.
Pokémon Snap, released in 1999 for the Nintendo 64, featured Pokémon shouting their names every which way while being photographed. A trend that only seemed to be relevant in games that had a specific tie to the anime. Handheld Pokémon games continued to use the cries from the original games, updating their shrill sounds over the years. Even in the latest entries the only Pokémon who actually speaks its own name is Pikachu, Pokémon's mascot who is known for just that.
While the Pokémon TV series is still going strong with the classic dialogue, it was surprising to see the 2013 anime special Pokémon Origins decided to pay homage to the original three titles by making their Pokémon emote with grunts and growls. It's certainly something that fans haven't seen much of in the realm of television or movie over the years.
The newest Pokémon title, Pokken Fighters for the Wii U, seems to have also picked the more realistic approach when it comes to Pokémon interaction. If you can call screaming at someone while you flame kick them interaction. Once again, the only Pokémon spouting its own name is Pikachu.
With the release of Pokémon Sun and Moon this spring, there's no doubt that the Pokémon brand is still going strong. Chances are we won't see the games or the anime ending any time soon. That being said, there doesn't seem to be a demand for anime tie-in titles like there was in the original Pokémon's heyday. It seems like The Pokémon Company is slowly but surely trying to distance the newest games, both console and handheld, from the anime's aggrandising communication. With the exception of Pikachu, of course. Pika Pika!