It turns out that they are from Team Rocket. They say that Pok mon trainers are so gullible. They are just taking their Pok mon and giving the best ones to the Boss. He takes a picture of the conveyor belt and the Breeding Center owners see the flash. We find out that their names are Butch and Cassidy.
Butch comes out to investigate.
Ash quickly puts Pikachu in a cage and tells it to spark a bit. Butch comes past and falls for it. He calls out to Cassidy that it was only the Pikachu making the flash. Ash decides it is time to leave. They are just about to when three figures appear coming out of a vent.