Pokémon Scarlet and Violet celebrates the Japanese golden week with (possibly) Golden Pokémon

Pokémon will celebrate Golden Week by having Golden Massive Outbreaks, though the available Pokémon don't look very golden. Golden Week is a Japanese custom where they celebrate different holidays in a row, prompting them to take a week off, and during this time (and a bit more), Pokémon Scarlet and Violet will have some Special Massive Outbreaks.

The Pokémon that will appear on the Massive Outbreaks are not Golden themselves, but their Shiny forms are. The event will last from Thursday, April 25th, to Monday, May 6th (or Friday, April 26th, to Monday, May 6th, depending on your Time Zone) and will have an increased chance of spawning Shiny Pokémon.

The Massive Outbreaks will be happening in all regions, Paldea having Massive Outbreaks for Varoom and Magikarp, and for those that have the DLC, Shinx will appear in Kitakami, while Rellor will appear in Blueberry Academy's Terarium.

You don't need to progress far into the game's story to participate in the event. All you need to do is gain access to the Poké Portal and then check the Poké Portal News inside the Mystery Gift menu. The event Mass Outbreaks will appear on your map with a golden icon. If you don't have the Pokémon from the outbreak registered on your Pokédex, it will appear as a question mark with a golden Mass Outbreak icon. To gain access to the Poké Portal, you only need to play the game for the first few hours.

To enter the DLC areas, you don't require to advance too much into the story either; you can start the Kitakami Storyline as soon as you gain free roam into the game, and shortly into the Kitakami storyline, you gain access to the Terarium (you'll have to participate in a difficult Pokémon Battle, but even if you lose you are still allowed in).