How do you get hitmonlee?

I belive it is at level 20 and you heve to have it's attack power higher than it's defense power. If you want Hitmonchan, you have to do the opisite. And if you want it to evolve into Hitmontop you must make it's attack and defense equal to each other. To make it's attack or defense higher, I would recomend using Proteins and Irons.

Protein: A nutritious drink for Pokemon. It raises the base Attack stat of a single Pokemon

Iron: A nutritious drink for Pokemon. It raises the base Defense stat of a single Pokemon