There will be Shared Skies themed stickers for sale in the
Shop.
Fusion Pokemon will make their debut during this season.
Necrozma will make its debut during Pokemon Go Fest.
Marshadow will makes it debut during Pokemon Go Fest.
One extra special trade per day (2 daily)
Increased XP for first catch of the day
Increased chance of Candy XL walking with your buddy
Different Pokémon will appear in the wild. Northern and Southern hemispheres will have exclusives.
Cities
Magneton

Houndour

Ralts

Makuhita

Skitty

Trubbish

Dedenne
Forests

Bellsprout

Ledyba

Sunkern
Linoone
Breloom

Skorupi

Foongus
Mountains

Diglett

Shuckle

Slakoth
Vibrava
Excadrill

Dwebble

Bunnelby
Water
Poliwhirl

Horsea

Chinchou

Surskit

Finneon

Tympole
Jellicent
Hemisphere-exclusive Pokémon
Some Pokémon will only appear in the northern hemisphere or southern Hemipshere.

Northern Hemisphere

Hisuian Growlithe

Skarmory

Treecko

Torchic

Mudkip

Clamperl

Beldum

Southern Hemisphere

Scyther

Hisuian Sneasel

Bagon

Turtwig

Chimchar

Piplup

Bronzor
Different Pokémon will be hatching from 2k, 5k, & 10k eggs. See the full list on the Eggs page.
Research Breakthrough
Complete Field Research to unlock Research Breakthrough encounters with one of the following Pokémon.

Hisuian Growlithe

Larvitar

Audino

Axew

Furfrou (Natural)
Jangmo-o
Free Monthly Timed Research
There will be free Timed Research every month during Shared Skies..