How to get a legendary pet in Adopt Me?

I'm curious about how to acquire a legendary pet in the popular game Adopt Me. Could you please explain the various methods or strategies that players can use to increase their chances of getting one? I've heard rumors about trading, completing quests, or even opening special eggs, but I'm not sure which route is the most effective. Is there a specific method that stands out as the most reliable way to add a legendary pet to my collection?