add your 5 sprites to a family. Instead of spawn sprite you just spawn family and this will pick one of the sprites from the family group at random
How to prevent your spawn point been picked straight away again…
give your spawn points Boolean instance variable (called for example "busy")
give your spawn points a timer behaviour
then in your code you will have an event which say something likeevery X seconds
add a 2nd condition which sayspick all the spawn points that are not "busy"
add a 3rd condition which saysfrom all of these available spawn points pick one at random
The action to this condition isfrom this spawn point spawn a member of the family
set the timer on this spawn point for a suitable delay
set the instant variable Boolean "busy" to true
add a new condition/action which sayswhen the spawn point timer is up reset its instance variable Boolean "busy" to false
Hope this makes sense?