Groudon (Japanese: グラードンGroudon) is the secondary antagonist of Jirachi: Wish Maker. It is not a true Groudon, instead being a corrupted, purely evil being that sought to absorb the energy from the earth.
Groudon Fossil in Butler's presentation to Team Magma
Butler was assigned by Team Magma to bring a Groudon back to life using a Fossil of the prehistoric Pokémon. However, his experiment failed, as his machine lacked the proper amount of power. Butler was exiled from Team Magma for his failure, leaving him with a growing resentment towards the organization. Butler then planned to use the power of the Millennium Comet to complete his experiment, but he needed a Jirachi, which could channel the comet's energy. Some time later, Butler found the Jirachi he had been searching for in the land of Forina.
After the Jirachi had awaken from its thousand-year sleep, Butler successfully finished his experiment. Unfortunately, his creation was pure evil, and began absorbing the energy from the earth as well as living organisms such as plants, people, and Pokémon; including May, Brock, Diane, Jessie, James, Meowth, and many nearby wild Pokémon; with gelatinous tentacles expelled from its spikes. After seeing the error of his ways, Butler decided to aid Ash in destroying his own creation by reversing the polarity of his machine. However, the Groudon had to be near the machine for it to work, and Jirachi had to once again charge the energy gained from the comet. Butler distracted the Groudon on his Salamence while Ash and Max rode on the back of a wildFlygon to Butler's machine. They barely escaped being absorbed themselves when Salamence swooped in front of the Flygon. Salamence, however, was caught in the tentacle, and Butler was sent falling to his doom, only to be rescued by Jirachi teleporting his Salamence under him just in time. Once Jirachi was fully charged, Butler, his Salamence, and the Flygon were caught by the Groudon, who had enveloped the machine with its enormous body. Jirachi unleashed its Doom Desire and sent the Groudon high in the air where it was completely obliterated.
After the Groudon was defeated, all of the people and Pokémon it had consumed were revitalized.
As this Groudon was not a real Pokémon, it lacked a personality. Due to it being created through Jirachi and Butler's selfish wishes, this Groudon-like being was a manifestation of pure evil, and it consumed people and Pokémon alike while sucking up energy from the earth. As such, it was deemed to be an abomination.
For more information on this Pokémon's species, see Groudon.