The only way you can get Tyrogue in HGSS is from Mt. Mortar, as a gift from the Saffron Dojo Master. The Dojo Master is hidden deep inside Mt. Mortar, training his Pokemon. You will have to defeat him in order to obtain the Tyrogue. He has two Pokemon - a Hitmonlee and Hitmonchan both Male at Lv. 34. You will need an empty slot in your party.
The Tyrogue will be at Lv. 10.
Hope I helped. :)
