Water Festival 2017

Water Festival in 2017 was the first Water Festival event in Pokémon GO.

Featured Pokémon
These Shiny Pokémon were released at the start of the event: PS Magikarp PS Gyarados

These Water-type Pokémon had increased spawn rates in the wild and from Incense or Lure Modules:

Avatar items
These avatar items/poses were released at the start of the event:

Trivia

 * Magikarp is the first Shiny Pokémon in the game.