Prepare the instant pudding first according to package direction by whipping the pudding with the cold milk until soft set. Refrigerate until firmed up, about 1 hour.
Sprinkle half of the diced angel food cake onto the bottom of a trifle bowl. Set aside a few of the blueberries, strawberries, and raspberries to decorate the top of the cake. Add half of the remaining berries evenly over the cake pieces, then spoon the set pudding on top of the berries.
Add the last layer of cake and any remaining berries (except those reserved for decoration). Top berries with frozen whipped topping, spreading gently to create a smooth and even surface. Use the reserved berries to decorate the top of your trifle however you'd like!
Serve immediately, or refrigerate until ready to serve (don't make too far in advance, as the cake will start to break down the longer it sits).