The problem with pet training is that players are upset when their pets don't get talents they want or can even use, and it takes a lot of time and effort to level up a pet and even a lot of crowns and money for those who choose to go with mega snack packs to save a bit of time.
Every time a pet levels up a player should be able to click on the talents they want to keep, and then all other talents should be randomly assigned. This means if you like the talents your pet has after it reaches teen you can click individually to keep them, if you don't like them you don't click to keep them and when your pet goes to adult it gets all new random talents.
The problem then is your last talent obtained when your pet turns epic. At that point a pet should be given the opportunity to returned back to ancient and then be able to be trained from ancient to epic again for another random roll. Contrarily, a pet owner could be given the opportunity to pay 50,000 gold or that value in crowns to reroll any one talent.