I got a Charging Bull hybrid on my storm. Then I was lucky enough to get another one. So I trained them up to mega and hatched them, I did it again and trained the offspring up to mega. So far so good. then I hatched the offspring together. The result is, that ALL of them are exactly the same. Pain Giver Spell Defying Pip-o-Plenty Incredibly Infallible Fire Ward. All of them, exactly the same. Is there something in the coding that won't allow these hybrids to gain any stats other than these? If there isn't a chance of getting a different talent, why bother?
It sounds like your pool is too similar and by manifesting the full 5 talents before hatching you could be lowering the chance of popping one of the other talents that haven't manifested so far.
If you want to keep going through self-hatches you could try making a couple of babies and only taking them to adult then hatching them together to see if any of the other 5 talents in the pool show up.
If you'd like to mix up the pool and have the best chance of changing the outcome I'd recommend either hatching with a different pet you have (that has good stats and desirable talents) and train up the baby when you get a bull from it. Or you could find someone with a nice bull and hatch with theirs so you can get some of their talents.
With the kiosk coming soon you might do best to wait and find a good bull on there to hatch with if you don't have a suitable pet to hatch with at the moment.
Sorry you got bad luck and I hope you get awesome talents soon! You can definitely get other talents on it, don't give up! Let me know how you get on, I might be able to help when the kiosk goes live Good luck!