Increased chance to become Lucky Friends
Increased chance to get Lucky Pokémon in trades
PokéStops may turn gold without a Golden Lure Module
Increased chance to encounter Shiny Pikachu wearing a cake hat and Shiny Eevee wearing a party hat from raids
Gimmighoul holding a 9th anniversary coin will have a 9th anniversary-themed Special Background
Friendship levels will increase faster than normal through opening Gifts, trading Pokémon, or battling together in raids, Gyms, or Trainer Battles
Chance of finding 9 or 99 (or maybe more!) Gimmighoul Coins when you spin a PokéStop with a Golden Lure Module
During the 9th Anniversary Party, you may discover party hats in the wild. Tapping on them will award items, or encounters with event-themed Pokémon
Also, for the first time in Pokémon GO, you might even encounter Shiny Gimmighoul—if you're lucky!
1/2 Egg Hatch Distance
2x XP for catching Pokémon
2x Stardust for catching Pokémon