Most Pokemon Go event have at least one or two surprises. While the Anniversary Event's main draw is a new Pikachu variant, the game also quietly changed its egg pools in conjunction with the event.
For those unfamiliar with Pokemon Go lingo, egg pools determine what Pokemon hatch from certain eggs. Pokemon Go has periodically tinkered with the egg pools, pulling out certain common Pokemon and adding rarer Pokemon from time to time.
Since these changes were made during the Anniversary Event, we don't know whether these changes are permanent or just a part of the event.
Keep scrolling down to see all of the changes:
The biggest "change" to the egg pool is the addition of "Ash Hat Pichu," a pint-sized version of the Pikachu that the new event is centered around. "Ash Hat Pichu" replaces the normal hatless Pichu for the duration of the event. Please note that any 2 KM egg obtained before the event started last week will not contain an Ash Hat Pichu, so focus on hatching new eggs if you want one of these rare Pokemon.
The other addition to the 2 KM egg pool is the addition of Spinarak, the Gen 2 Bug-Type Pokemon. Spinarak's addition is a bit strange as its one of the more common Pokemon from the newer Generation of Pokemon and Pokemon Go usually removes common Pokemon from the pool.
Chikorita, Cyndaquil, Totodile, Hoppip, Wooper, Swinub, Snubull, Natu, Marill, Teddiursa, Houndour
This list includes most of the Pokemon that were initially left out of the egg pools when Pokemon Go first added Gen 2 Pokemon earlier this year. Pokemon like Chikorita, Totodile, and Teddiursa were initially excluded from the egg pools, much to the frustration of players who lived in areas where those Pokemon were rare.
Both Wooper and Natu were initially included in the egg pools but were pulled out last month as part of a rebalancing update.
Three Pokemon were also dropped from the 10 KM egg pool to the 5 KM egg pool. Mantine, Pineco, and Gligar were all "demoted" from the rarer egg pool group as part of the big changes.
To make up for the loss of three Pokemon from the already small 10 KM egg pool, Pokemon Go pulled a Pokemon from the 5 KM egg pool back to the 10 KM egg pool. Porygon has flip-flopped between the 5 KM and 10 KM egg pool multiple times, so this isn't necessarily a permanent change.
Chinchou was also added to the 10 KM egg pool. Like many other Gen 2 Pokemon, Chinchou wasn't in the egg pool when Gen 2 Pokemon were first added to the game. However, Chinchou isn't exactly a rare Pokemon so we're not sure why this Pokemon got put into the egg pool as opposed to keeping Gilgar or Pineco in the 10 KM pool.
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