Add the undrained pineapple and pudding mix to a large bowl. Stir until smooth. Add in the well-drained mandarin oranges, mini marshmallows, and coarsely chopped pistachios. (if desired, add in fruit cocktail here.) Gently fold together until combined.
Using a spatula, gently fold in the thawed frozen whipped topping until all the ingredients are well covered. Cover and refrigerate for 45 minutes to an hour. Serve chilled with a sprinkle of shredded coconut or additional crushed pistachios if desired.