The more normal outbreak is becoming, the more often we will see hybrids. Like explained by ahri, if a parent is an outbreak holder and the other is not then the offspring will have 50% of the outbreak. Now if the offspring of that one, was to be created then that one would have less outbreak and more it goes down the line, the less and less it goes away.

Now for moons case her being a healer, her outbreak will die off in future generations as it cannot replicate as much as it would in a normal outbreak creature.

Birth defects are a common thing among them, as the outbreak does alter and mutate the body. Though it depends on the host, it is possessing. For example trigs, he was altered due to his outbreak being able to have a bigger effect on his physical form rather then most.

Another one is cav dragon blod, for Blod its a bit mix of two things diet and physical appearance. Blod appearance is a lot more slimmer then some, and having two giant fangs sticking up from her bottom jaw. Her diet is a dead giveaway, as her name gives off the hint. She is a lot more ravenous then the others and tends to like her food fresh.

The birth defects only means the outbreak has more control over certain parts of the creatures bodies, either be physical, mentally or even just diet wise.

The mental ones are always rare to run into, due to them being locked up or kept close within the hive, though there is one in rainbow/night haven. Who it is, will be revealed later on. Now, the reason why the mentally altered ones are kept close or locked away is because of how unstable they can be, at times they'll have control over themselves and the next the outbreak will take over. Its why the hives keep them close, not knowing when they will lash out.

Can this be avoided in future generations? Yes, again since the outbreak isn't really a recessive gene the offspring will have a less chance on getting these defects. What if the parent is one of the ones with the defects? It is likely the kid will get it, but it probably wouldn't be as strong as it is for the parents.