Players can find and capture Groudon, Kyogre, and Rayquaza in Pokémon Brilliant Diamond & Shining Pearl. It's important to mention that players will only have access to these Pokémon after beating the main story and becoming the Champion.
Once this is done, players will be tasked with completing the remainder of their Sinnoh Dex. Players just need to see all 151 Pokémon in the region for it to count.
This is how players can get the National Dex and unlock new caves with Ramanas Park. Groudon,
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