To a large bowl, add the pistachio pudding mix, crushed pineapple with its juice, miniature marshmallows, 8 ounces of whipped topping, and 1⁄2 cup of the walnuts. Refrigerate until ready to use.
3.4 ounces pistachio-flavored instant pudding mix, 20 ounces crushed pineapple, 1 cup miniature marshmallows, 8 ounces whipped topping