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.
300 skeletons broken
1000 presents smashed
Go Green, Get Lucky finished
300 Cookies broken
300 flowers picked
300 pots of gold broken
300 Piggy Bunnies popped
Easter Eggs finished
300 chocolate boxes broken
Hogs and Kisses finished
300 pumpkins smashed
300 lanterns broken
300 pigs smashed
Orange Bird unlocked
Finish Trick or Treat
Finish all Season's Greedings levels
Finish all Summer Pignic' levels
Finish Moon Festival
Finish Ham'o'ween
Finish Wreck the Halls