Sure~! [Wait. Does she even have an answer for this question?! UMMM.] Well, think about breeders. They don't need to challenge the gyms, but I guess [HOPE!] they don't want their pokemon to do anything if the pokemon are still little babies themselves. And some pokemon want to battle even when their trainer doesn't want to challenge the gyms, they'd get bored without doing anything. And, if the pokemon likes training, it gives you something to do with them here.