For fans of the Pokemon anime, Pikachu "tallking" has always been pika-pika noise. And the voice of Pikachu has been Ikue Otani. Yes, the Pokemon Dungeon games have the Pocket Monster talk to each other with in-game text. But this, this is just messed up.
The newest entry's latest teaser brings that to life with anime trailer that features full voice—and not Otani's. In the trailer, that's Rie Kugimiya bringing the gum-flapping Pikachu to life.
For more on talking Pokemon, the Bulbapedia has a great rundown.