The cartoon I watched was multiple episodes in 2006~2015 on "Cartoon network" (Don't remember the exact timeline). The main thing I remember is that the main characters are two boys and one girl (around 10-12 years old). The two boys had something like ancient China's ki. The girl can control water. They are in the same sect fighting an evil sect.
I also remember a particular episode:
- The three main characters fight in some cave and the girl get split away from the other two and gets captured by the evil sect. The two boys get lost and find something like an clock made of gold and go to the future. In the future, they see they had mastered their ki and were fighting the girl who had joined the evil sect because she had been left alone in that cave. With the help of their future selves, they get back to the cave and save the girl in time. But when all three go back to the clock, it had dissapeared.