Gekkouga is the Japanese name for Greninja, and Satoshi is Ash Ketchum's Japanese name, so Satoshi Gekkouga refers to their shared Ash-Greninja form. The bond transformation became a defining part of the Pokémon XY and XY&Z anime, where Greninja took on markings resembling Ash during battle. Clips and edits of the transformation spread widely through YouTube, anime forums and Pokémon fan communities, keeping the theme popular for edits long after the season ended because it instantly identifies that specific partnership.