Before we can get a proper list of Shiny Event Pokémon, we need to define what counts as an "event."
- Something needs to be distributed. This technically includes items as well, but for our purposes, our list will only include Pokémon that were distributed. If there's no Pokémon distributed, then there can't be a shiny Pokémon.
- An external trigger outside of the game needs to take place. Players can connect to the Internet to trigger an event distribution, but the player cannot only take part in an in-game sequence to trigger the event, such as shiny Gift Pokémon.
- Events have to be officially sanctioned by affiliated parties at some point. Methods used to access an old event are fair game here, as this list serves to compile a list of event distributions. However, any recreations, modifications, or outright custom events do not qualify (at that point, anyone could create an event and add it to the list).
- Shiny status must be guaranteed. Any event distributions that have a chance of being shiny do not apply to this list (this only impacts a single Pokémon, Arceus during the Archjinni of the Rings Hoopa movie promotion).
- Events with boosted shiny odds, such as spotlight raid events in Sw and Sh or outbreak events in Sc and Vi do not count. However, events that only trigger shiny encounters, do count.
That being said, now we need to discuss which Pokémon are eligible for this list. While this list strives to show which Pokémon were distributed thanks to events, many Pokémon on this list could further evolve, either at the time of the event or later in the future. Further, do temporary forms, such as Mega Evolution and Gigantamax Pokémon, get an additional entry in this list?
In my personal opinion, I only count Pokémon forms that could dedicate a spot in a box in a collection. Pokémon can evolve and fill a new role in a collection, but I personally have trouble justifying Mega Evolutions and Gigantamax Forms since those are changes that happen during battle and reset when conditions are filled. But I can understand arguments for both of those questions. As such, both evolutions and special forms will be included in this list when possible, but as a part of their own sections separate from the strictly "event" shiny Pokémon.
For future proofing reasons, however, I will not count any Pokémon forms that are "undone" went moved out of a game into Pokémon HOME or similar. This includes any costumed Pokémon in Pokémon GO, any Shadowed forms, or anything along those lines. To my knowledge, that does not apply as of writing, but I would not be surprised if that eventually became a factor later.
If you would like to skip ahead, feel free to jump ahead to one of these sections. Or, you can use your browser's Search tool to search for a given Pokémon's full name or a National Dex Number.