In a large bowl, stir the undrained crushed pineapple and instant vanilla pudding mix for about 2 minutes, until the powder dissolves and the mixture begins to thicken.
Gently fold in the thawed whipped topping until smooth.
Fold in the mini marshmallows, coconut, and optional chopped nuts and cherries until evenly distributed.
Cover and refrigerate for at least 1 hour so the dessert firms up and the flavors blend.
Serve chilled. If desired, garnish with extra whipped topping, pineapple, toasted coconut, or a cherry.