How do you get hitmonlee on Pokemon SoulSilver?

You can obtain a Hitmonlee in Pokémon SoulSilver by using a Tyrogue and raising its Attack stat. To obtain a Tyrogue, you will need to first catch a Hitmonchan or a Hitmontop in the wild. Once you have one, you can breed them with a Ditto at the Pokémon Day Care. The egg hatched from this pairing is guaranteed to be a Tyrogue.

To raise Tyrogue's attack stat, you will need to have it battle and defeat other Pokemon. Each time Tyrogue levels up, its stats will increase, and eventually, its Attack stat will be higher than its Defense stat. Once this happens, it will evolve into Hitmonlee.