Unfortunately, Ash-Greninja cannot be sent to or used in Pokémon Sword, Shield, Brilliant Diamond, or Shining Pearl. This is because Ash-Greninja is a unique form of Greninja that was specifically designed for Ash Ketchum, the main character in the Pokémon anime series.
Ash-Greninja made its debut in the Pokémon XY and Z anime series, where it showcased its incredible power and unique appearance. It gained popularity among fans, who were eager to obtain their own Ash-Greninja in the games. However, Game Freak, the developers of the Pokémon games, decided to keep Ash-Greninja exclusive to the anime and not make it available in the mainline games.
It’s important to note that Ash-Greninja is not considered a separate Pokémon species, but rather a special form of Greninja. This means that regular Greninja can be obtained and used in Pokémon Sword, Shield, Brilliant Diamond, and Shining Pearl, but it will not have the unique characteristics and appearance of Ash-Greninja.
While it may be disappointing for fans who were hoping to use Ash-Greninja in these games, there are still plenty of other Pokémon to discover and train. Each game offers a wide variety of Pokémon species, each with their own unique abilities and strategies. So, even without Ash-Greninja, there are still countless exciting Pokémon to catch and train in these games.
Ash-Greninja cannot be sent to or used in Pokémon Sword, Shield, Brilliant Diamond, or Shining Pearl. It remains exclusive to the Pokémon anime series and is not available as a playable Pokémon in the mainline games. However, there are still many other exciting Pokémon to discover and train in these games, providing plenty of opportunities for exciting battles and adventures.