Romantic adventure fanfiction featuring Groudon and Kyogre is a wonderfully specific niche, and I totally get the appeal of exploring that dynamic. The sheer scale of their conflict in the Hoenn lore—literal continents reshaped by their clashing—lends itself perfectly to epic, world-spanning journeys where a bond might form amidst the chaos. That primal, elemental opposition creates a tension that's ripe for storytelling, where mutual respect or even affection has to be forged against a backdrop of cataclysmic power.
Your primary hunting ground should absolutely be Archive of Our Own (AO3). The tagging system there is your best friend. I'd start with the 'Pokémon' fandom tag, then use the relationship tag 'Groudon/Kyogre'. To narrow it down, combine that with additional tags like 'Adventure', 'Slow Burn', 'Alternate Universe - Canon Divergence', or 'Pre-Canon'. Sometimes authors use 'Elemental Bonding' or 'Ancient Pokémon' as tags, which can lead to real gems. Don't forget to sort by kudos or bookmarks to find the most beloved stories in the pairing.
You could also check out FanFiction.net, though the search functionality is less precise. Browse the 'Pokémon' category and look for stories categorized under 'Adventure' and 'Romance'. Using the site's search bar with the pairing name might yield results, but you'll likely need to sift through more cross-pairing fics. Some writers also share snippets or longer works on Tumblr or Twitter, using hashtags like #Pokefic or #GroudonKyogre. Finding those feels a bit more like a community deep dive, asking around in dedicated Pokémon fan spaces.
What I love about this pairing's adventure stories is how they often reimagine Hoenn's ancient history, weaving in lore from games like 'Pokémon Omega Ruby' and 'Alpha Sapphire' to build a setting where these two titans aren't just mindless forces of nature. The adventure element lets writers send them across oceans and volcanoes, maybe on a reluctant quest to stop a greater threat, forcing them into an alliance that gradually deepens. The emotional core usually hinges on understanding and communication transcending their innate opposition, which makes for a really satisfying character arc amid all the action. I found one a while back that had them seeking out Rayquaza to mediate a truce, and the journey was full of these quiet, surprisingly tender moments built around shared exhaustion and awe at the world they'd helped create.