Full list of all 20 Angry Birds Seasons achievements worth 200 gamerscore. It takes around 10-12 hours to unlock all of the achievements on Windows Phone.
All achievements
Achievements they've won
Achievements they've not won
Pick 300 flowers
Finish all Summer Pignic' levels
Finish Ham'o'ween
Break 300 skeletons
Break 300 lanterns
Finish Moon Festival
Break 300 chocolate boxes
Finish Hogs and Kisses
Finish Trick or Treat
Finish all Season's Greedings levels
Pop 300 Piggy Bunnies
Finish Easter Eggs
Finish Go Green, Get Lucky
Break 300 pots of gold
Smash 300 pumpkins
Break 300 Cookies
Smash 1000 presents
Finish Wreck the Halls
Smash 300 pigs
Unlock Orange Bird