In The Game-Corner
For 6,000 coins
In Pokemon HeartGold, there's two Game Corner buildings.
The first Game Corner is in Goldenrod City. The building is directly next to the Pokemon Center to the north. There's a Rocket grunt outside the building if you haven't defeated Team Rocket in the main story.
The second Game Corner is in Celedon City in Kanto in southern part of the city.
The One You Wan't To Go To IS In (Goldenrod-City)
To get (TM) Rest hope I helped :)
Like ( blobyolo) Said Here Is a list of all the TM's In Heart-Gold And Soul Silver
Credit's to (blobyolo)
EDIT:You can get It after(delivering the NPC's Spearow It should be on(Route 44)