BioArnold lives with his mother in Hophophop Town, a large city where the Pokémon Fan Club was using their Hypno and Drowzee to help their members get to sleep. The members of the Pokémon Fan Club were unaware that it was causing side effects with the children in the town including Arnold. Arnold's Mother was searching for Arnold after he went missing and mistook Ash for Arnold because according to her, Ash just looked like her son.
Ash and his friends decided to help out Arnold's Mother and try to find out where Arnold had disappeared to. After Ash and his friends with the help of Officer Jenny tracked down the kids to a park in the middle of Hophophop Town, Arnold's Mother randomly showed up in the park and was reunited with her son.