My home Block and stucco, and has been painted twice with elastomeric paint. According to the Home depot once painted with elastomeric paint it must always be painted with it?
You can paint over the elastomeric with a very good 100% acrylic exterior house paint with a minimum satin sheen. Priming shouldn't be needed but consult with the maker of the latest coat of elastomeric. Each manufacture has their own recommendations for their products.
The reason why I know this is I was contracted to paint a building with a Porter elastomeric and the owner just wanted a fresh look, same color. The recommendation was wash with tsp and pressure washer, look for any peeling and spot prime raw areas with an acrylic primer then paint with a good standard house paint.