* Groudon is a legendary Pokémon: Legendary Pokémon, with a few exceptions, are generally not designed to be re-battled in the main story of Pokémon games.
* Specific to SoulSilver: Groudon is a part of the "Pokémon Ruby" storyline, and SoulSilver is based on the "Pokémon Silver" storyline. The legendary Pokémon from opposing versions (Ruby vs. Silver) are not available to battle again.
However, there are ways to encounter Groudon in SoulSilver through alternative means:
* Trading: If you have access to a Pokémon Ruby, Sapphire, or Emerald game, you can trade a Groudon from that game into your SoulSilver game.
* Events: Occasionally, Nintendo might hold special events where you can receive certain legendary Pokémon, including Groudon, in Pokémon games. Keep an eye out for announcements if you're interested in acquiring Groudon this way.
Let me know if you have any other Pokémon questions!