You develop a PPT to engage your target-audiences. You put in different elements to make it noticeable and informative. All the creativity-pursuits are to fetch the attention of the audiences. All the elements must be proportionately used and placed in sync with each other. Animation is one of those elements which you craft to facilitate better understanding of the real message for your target-audiences. You can use it in different ways to enhance the impact of your PPT:
Bear in mind, an animation in a PPT must not break the flow of the presentation. It augurs well when it is used well. Deliberate and premeditated use might backfire.