To write a Naruto x Yugioh Zexal fanfic, start with an idea that ties the two together. It could be based on a shared theme like friendship or power. Next, plan out your story structure. Have a clear beginning, middle, and end. In the beginning, introduce the situation that brings Naruto characters into the Yugioh Zexal realm. In the middle, build up the conflict, whether it's a tournament or a fight against an evil force. At the end, resolve the conflict in a satisfying way. Also, use vivid descriptions to bring the duels and ninja actions to life. For instance, describe how a character summons a powerful card as if it were a ninja jutsu, with a big flash of light and a lot of energy.