The freestyle roller skating world championship is what you call the international inline skating plane fancy roller skating competition!
Champions should be divided into different groups, different events and different years!
I don't know what year, event and category you want to know.
Here are some references for world champions:
Adult Men's Group: Seba (France), KSJ (Korea), Li Jinxi (China)
Adult women's group: Chen Chen (China) (won the women's group world championship for three consecutive years)
Young women's group: Su Feiqian (China) and Chen Chen (China) (before joining the women's group)
Young Men's Team: Pu Haoyang (China)