(wikipedia):
Chen taijiquan and learning from 2nd gen baguazhang masters:
Fu Zhensong was born in Mapo village, Biyang County, Henan province, China. When he was 16 years old, he joined his village's newly created martial arts school, where he studied under Chen Yanxi (陳延禧) from the nearby Chen village, an 8th generation disciple of Chen family of taijiquan. He also learned from Chia Feng Ming (賈山) (also written in English sometimes as Chia Chi-shan or Jia Feng Meng), a top student of the founder of baguazhang, Grandmaster Dong Haichuan. After nine years of training, his teachers encouraged him to move to Beijing to learn more. When he moved to Beijing, Fu continued his studies of baguazhang with Ma Gui and Cheng Tinghua, both first generation disciples of Dong Haichuan.
Sun taijiquan and xingyiquan and Yang taijiquan
In Beijing, Fu met Sun Lu-t'ang, Yang Chengfu, and many other skilled practitioners, with whom he exchanged knowledge. This exchange continued when the Central Guoshu Institute (Central Martial Arts Academy) was founded in Nanjing. After heavy competition, Fu Chen Sung was made Chief Instructor of baguazhang, emphasizing in his teachings fast precise footwork and waist strength. It was here that he taught Sun Lu-t'ang the Wudang sword and in exchange, Sun Lu-t'ang taught him the Sun-style of Xingyiquan and T'ai chi ch'uan.
Beating Yang at push hands?
During this time, Fu met, befriended and exchanged information with the top Baguazhang masters of China. He became close friends with Sun Lu-t'ang, and taught him the Baguazhang "mud-walking step (tang ni bu)." Fu studied Yang-style taiji from Yang Cheng Fu, and one day beat him in a match of "push hands." Yang said, "You only won because you switched to Baguazhang." Fu also studied swordsmanship with Li Jing Lin.[4]