Does Plyometric and functional training promote lean muscle?

Hello Wenghonn Kan,
If done properly and incorporated into cross training, I don’t see why not. Remember, balance makes anyone better at what they do. Here is something you may like to read:

http://www.ideafit.com/answers/what-are-the-benefits-of-plyometrics

Take care,
Natalie aka NAPS 2 B Fit.