Many waste money hatching regular pets - like the Fire Cat with the Cyclops. They are wasting time. All they might get is another one of their pet or their friends pet, only the pet might have a special ability from its parent. You can only hatch level 48 pets. For example, a Satyr and Helephant can make a forest oni or burning tree thing, or maybe just ANOTHER Satyr or Helephant.
Pets have talents. Use the talents wisely. If a pet has a colossus and helephant as parents they might be a helephant with the colossus's talents.