Your solution is really not the best. Imagine there is only one enemy left. He would stop every second. "Repeat Sprite.Counts times" and then "Pick random instance" does not really make sense either. It could affect one enemy several times and others not at all.
My example did not contain the complete code to set the sprites in motion, it should only explain the principle. Of course you have to adapt it to your project.
Here again an example with everything that is necessary. Make sure that the conditions 'is moving' and 'is on floor' are really true. Disable one of the two if nothing happens.
1drv.ms/u/s!Ap_-qxoGKbDcg2IaHe7qBjaltMzA
Once again, it shows the principle. Adapt it to your project!