They are in the Safari Zone
There is no mossy rock in HeartGold. There is not one in SoulSilver, either. A mossy rock is only found in Pokemon Diamond and Pearl. You must trade for a Leafeon to get one in Pokemon HeartGold.
there's no moss rock in heartgold/soulsilver. To get it you need to trade from a different game. Sorry!
Pallet town
you get it AFTER you beat blue
There is it is in ilex forest
Possibly in the forest
Digletts Cave.
safari zone and rock tunnel.
If you have a Pokemon that has a rock type move, then you can easily win. Rock slide works the best.
You need to do the last gym in kanto.
you get it from oak after beating blue
In Pokemon HeartGold and SoulSilver Versions, HM08 Rock Climb is not needed to get to Seafoam Islands, HM03 Surf is though.