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Invisible shiny Bulbasaur (so named because it has no sprite, sparkles when it appears like a shiny Pokémon, and uses Bulbasaur's cry) is a glitch Pokémon found in Sinnoh's Oreburgh Mine. This glitch can also be found using Action Replay with the "walk through anything" code activated and by having a partner with you for wild Pokemon double battles. To encounter Invisible shiny Bulbasaur by doing so, you need to walk into any lake or ocean, making sure you have a partner and then encountering a Pokemon. The glitch will also make you have two versions of yourself, one having a name like "!!!!!!!!!!????????!!!!!!!!! 111!!!!!0" and he will send out a " " which will also be an Invisible Shiny Bulbasaur. Please note that you cannot catch this Pokemon during the battle because it has 0 HP and only knows the move "Struggle." You also cannot catch the Tentacruel or Pelipper with it because you cannot catch a wild Pokemon in a wild double battle.
When it appears, it is level 0 and has zero HP, much like ?????????? in Generation III. If it is attacked, the game will assume there is no target and end the battle immediately.
External links
Video of an encounter with this glitch