In a large mixing bowl, combine the instant vanilla pudding mix with the crushed pineapple and its juice until no streaks remain.
Gently fold in the Cool Whip until fully incorporated, taking care not to deflate the Cool Whip.
Add the mini marshmallows, shredded coconut, and chopped pecans to the bowl, and fold to evenly distribute the ingredients.
Refrigerate the mixture for 2-4 hours to allow the flavors to meld and the texture to set.
Just before serving, top the Pineapple Fluff with additional crushed pineapple, chopped pecans, mini marshmallows, and shredded coconut for an extra burst of flavor and texture.