1) Tai Lung - He is considered to be 40 years old during the events of KFP1. He was probably 20 during his betrayal and it is assumed that Po and the Five were born at this time.
2) Lord Shen - He is considered to be 40-50 during the events of KFP2. He was probably 20 when he led the genocidal campaigns. He waited 30 years preparing the canons. But this contradicts the theory that Shen killed Snow Leopards and orphaned Tai Lung.
3) General Kai - He is 500 years old. In my headcanon, I believe he is the same age as the first 2 when he formed an alliance with Oogway.
4) The Chameleon - I believe she is so also the same age. Between 40 to 50. That means when she was young , the Five were probably just younglings. So they had not mastered their styles.
What do you guys think ?