was first revealed in the October 2015 issue
of Corocoro. Ash's Greninja
is the evolved form of Ash's Frogadier
and it takes on a mysterious new appearance in the latest season of Pocket Monsters XY&Z. Ash-Greninja is the form that Greninja takes when the bond between it and Ash Ketchum
is raised to the limit. The strength of their bond changes Greninja's appearance and it takes on the characteristic look of Ash Ketchum
's attire. This phenomenon is also said to have happened just once several hundred years ago in the Kalos region, but it remains shrouded in mystery.