How many extra Candies does Pinap Berry grant?
It does exactly grant the double amount of candy for each stage of evolution. Don't bother the incorrect report of 5, 9, or 19 candies. They are being added to your candy total as 6 for stage 1 pokemon (eg. Pidgey), 10 for stage 2 pokemon (eg. Pidgeotto), and 20 for stage 3 pokemon (eg. Pidgeot) when captured using Pinap Berry.
Tested and verified by myself.
Screenshots added below illustrating the candy count problem.
