Question is "Who would win a battle of Hulk and Hanuman ji". So it is a fight between a FICTIONAL Character and Mythological GOD. One thing to be noted here, Fictional character's characteristics vary from time to time increasing (or decreasing sometimes) character's power set. read more
Brahma said that nobody would be able to kill Hanuman with any weapon in a war. Vishwakarma blessed him with invulnerability too Yama blessed him with immortality. That by itself should make Hanuman victorious in any battle, but the author put forth Superman’s powers too. Image source. Which are incredible. read more