Until Dec. 12 at 4 p.m. ET, special Field Research Tasks that reward evolution items will be able to be grabbed from PokéStops. Onix, Eevee, Roselia, and Burmy will also spawn more frequently in the wild and Lickitung, Scyther, Togetic, and Ralts will be featured in raids.
To make the most of this event, grab as many Roselia, Ralts, Scyther, and Togetic as you can. Roserade and Scyther are both great grass- and bug-type attackers respectively. Gardevoir and Togekiss top the charts as fairy-type attackers as well.
XP from evolving Pokémon will also be doubled, so if you have a lot of Pokémon that have low Candy costs to evolve, like Caterpie, you can mass evolve those while using a Lucky Egg for some good gains.
Burmy will also be spawning Shiny for the first time.
Pokémon Go Evolution Event 2019 Field Research and rewards
|Evolution Event: Catch 10 Horsea||Dragon Scale|
|Evolution Event: Catch 10 Poliwag or Slowpoke||King's Rock|
|Evolution Event: Catch 10 Sunkern||Sunstone|
|Evolution Event: Catch 5 Onix||Metal Coat|
|Evolution Event: Catch 5 Porygon||Up-Grade|
|Evolution Event: Evolve 10 Pokémon||Burmy encounter|
|Evolution Event: Evolve 5 Pokémon||1,000 Stardust|
|Evolution Event: Evolve a Feebas||3 Rare Candy|
|Evolution Event: Evolve an Onix||Scyther encounter|
|Evolution Event: Hatch 7 eggs||Sinnoh Stone|
|Evolution Event: Use an item to evolve a Pokémon||Clamperl encounter|
|Evolution Event: Win 3 times against Team Go Rocket leaders||Unova Stone|
|Evolution Event: Win 5 raids||Magnetic, Mossy, or Glacial Lure|
The event ends on Dec. 12 at 4 p.m. ET.