First, do research on zoroark's characteristics and behavior in the Pokémon universe. Then, create a detailed plot that focuses on the pregnancy aspect. For example, how the zoroark's life changes during this period.
To write a good zoroark pregnant fanfiction, it's important to give the story a unique perspective. Maybe tell it from the point of view of the unborn zoroark's sibling. Also, make the setting realistic within the Pokémon world. For instance, if it takes place in a forest, describe how the forest environment affects the zoroark's pregnancy. And finally, have a satisfying ending, whether it's a happy one with the birth of healthy offspring or a more bittersweet one that teaches a lesson.
You need to develop interesting characters around the pregnant zoroark. These could be friends, foes, or other Pokémon that interact with it. Also, use vivid descriptions of the zoroark's emotions, like its excitement or fear about becoming a parent. And don't forget to add some conflict to make the story engaging, such as a natural disaster threatening the zoroark's pregnancy.