Just set up a render tree on the point cloud that uses an image sequence, and then use an ICE attribute to drive the Time Source of the image sequence.
First, here’s a basic render tree for the point cloud:
In the ICE Tree for the point cloud, you can set up an attribute that will be used as the Time Source for the image sequence. For example, suppose you wanted to randomly display a sprite from a sequence. In the ICE Tree, you could put a random number in an attribute for each particle.
Then you could use that attribute to drive the Time Source of the image sequence: