Mushu is a Chinese dragon and guardian spirit assigned by the Fa family ancestors to watch over the young Fa Mulan in her journey to battle Shan Yu and the other forces who threaten China in Disney Heroes vs Villains. Though he doesn't seem like the most capable guardian, his loyalty to Mulan is never in question.
The eccentric scientist Jack Spicer and his ally, the Heylin witch Wuya, were on the search for the fabled Shen Gong Wu's parts. Their first location is Danville and their targets were Phineas and his friends. Jack proved to be more challenging than the step-brothers anticipated.
Introducing Phineas and Ferb
Mushu introduced Mulan, Donald, and Goofy to Phineas, Ferb, and their friends who agreed to help them on their mission.