Here is the full list of all 29 Watch Your Plastic Duck achievements.
Get a duck with all stats from 10
Get a duck with any stat equal to 20
Get a duck that drowns 10 ducks
Get a duck that drowns 5 ducks
Get duck level 10
Get a duck with any stat equal to 10
Get a duck that drowned 1 duck
Get a glitchy duck
Get duck level 5
Use easel and change duck
Touch the pumpkin
Click various objects 5000 times
Click various objects 500 times
Click various objects 50 times
Click various objects 5 times
Thaw out a prehistoric duck
Collect 50 ducks
Mass extinction
Watch ducks for 5 hours straight
Especiallly dragon fire
I want to believe
Collect 25 ducks
Call the priest!
Witness the rainbow duck
Collect 5 ducks
And the sky is gray
Touch the gift
Get duck level 20
Get a duck with all stats from 20