Shatter tricked Charming Dazz into eating an enchanted candy, claiming it was a normal hard candy. Dazz ate it and learns quickly it wasn't a normal candy because she turns into a foal seconds later, she gets upset right away and in the midst of her anger, she uses her magic out of her control and regresses Shatter into a foal as well. It's common knowledge that baby unicorns don't have good control of their magic and they will have sudden bursts of magic. That's what happened with an age regressed Dazz. So yeah, Shatter's plan to take care of Dazz backfired and until they both turn back to normal, they need an adult to care for them.

There's a chance that Dazz will get her revenge next time.