What kind of fighting is used in?

There isn't a specific style there at all; it's videogame inspired martial arts. However, the movie was made with the istance of Jackie Chan's stunt team (as far as I remember), which means the moves are technically ... Well, Peking Opera Kung Fu. Master Yu Jim Yuen was a northern kung fu practitioner, and was the one that trained Jackie Chan (and Sammo Hung, and Yuen Biao, and so on). One presumes that Jackie Chan has trained or at least modified the styles of his stunt team, which means that the lineage is about as clear as it can be.