It can only be obtained via the Time Capsule exploit with Togetic or by using a catch trainers Pokémon cheat in unison with a wild Pokémon editor, using a value of D7. Attempting to encounter this pokemon with the Mew glitch will lead to a battle with a Swimmer. It will turn into a B (D7) if traded to Yellow. It has an alarming, machine-gun-like cry. When its summary is viewed, it plays a distorted fragment of an overworld song based on the area the player is in. After a moment the sound disappears.
This glitch Pokémon article is part of Project GlitchDex, a Bulbapedia project that aims to write comprehensive articles on glitches in the Pokémon games.