From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
Chin Taiken was a famous martial artist in the city and his strength was the real deal according to Dragon Ball: Daizenshū 7. He was to fight against Tenron of the Leopard-Fang School in a match held before the king. He staked his name as a martial artist on defeating Tenron, and aimed to restore the Chinke-Seikyoku-Ken, but an illness caused him to abandon the match. He then asked Son Goku to participate in his place. When he had a match with Goku, he fought using a free command of the main points of the Chinke-Seikyoku-Ken, but was not even able to realize when he had been attacked by Goku.
Fortuneteller Baba Saga
When Son Goku was looking for someone strong to test his power against, an old lady replied that a man named Chin was the strongest person around. Goku ran into Chin's son, Chin Shoken, who had allegedly stolen the wallet of Rising Dragon – a member of the Panther-Fang School.
The Chin-Star School and the Panther-Fang School were bitter rivals, so Chin was eager to defend his school and his son. Chin then used his signature technique, the Phantom-Star (a variation of the Afterimage), on two of of Rising Dragon's goons. When he was ready to fight an awestruck Rising Dragon, he buckled due to his sickness. After Sky Dragon broke up the scuffle between his brother and Goku, Master Chin agreed to a sparring session with Goku, but once again his sickness got the better of him.
By now, Chin's sickness is so bad that he cannot compete in King Wonton's martial arts competition against Sky Dragon to decide who is the master of martial arts. After deciding that his son, Shoken is not yet ready, Chin agrees that Goku should take his place. Goku wins the match by using Chin's technique and Chin is then named "The Master of Martial Arts". After the match, Chin and Sky finally put the past behind them as Sky starts anew under Chin as a member of the Chin-Star School.