In a 9x13 baking dish, carefully place each twinkie slice with the frosting side up in an even layer. You may have an extra depending on spacing.
In a small bowl, remove 2 tablespoons of the pudding mix and set aside. In a large bowl, whisk the remaining pudding mix with the milk until thick.
Gently fold in the diced mangos using a spatula.
Pour the pudding mixture over the twinkies and spread evenly across the layer.
Place the pineapple slices evenly over the pudding layer.
In another bowl, briefly whisk together the thawed whipped topping with the reserved pudding mix until slightly thickened.
Gently spread the whipped topping mixture over the pineapple in a smooth, even layer, covering the top of the filling completely.
Cover loosely with plastic wrap and refrigerate for at least 2 hours, or up to overnight.Before serving, top with cherries, chopped pecans, and coconut flakes if desired. Slice and serve chilled.