It is in the National Park above Goldenrod City.
Go to the national park and from there you should be able to the pokeathlon dome in poke mon heart gold.
You can get it in Johto by coming 1st in the National Park's Bug catching competition, You can also get it by winning events in the Pokeathlon Dome In Kanto, one way to get it is to show Bill a Marril In Heart Gold, or show him a Staryu in Soul Silver Or you could just wait for the Girl on Route 42 to ring you (if you have her number) she gives you items, mainly evolution stones.
I think you can with action replay or pal park. But the rest is trading
The Pokéathlon Dome is a location in Johto, west of the National Park. It is the place where Pokéathlon competitions are held.
in heart gold, you could get a kakuna in the national park when it's Tuesday, Thursday, and Saturday which is when the bug catching contest is.
you have to go to the pal park and enter the catching show it's in route 221
In the National Park, you have to enter the Bug Catching Contest and it is also very rare.
In fuchsia city.
johto national park
Well you enter the bug catching contest at the national park only on tuesday,thursday,saterday.by the way im 7 years old.
If the guard is behind the desk that's in the building before you enter into the National Park then that means the Bug-Catching Contest is not running that day.
Go north of goldenrod city and into the national park make sure its Tuesday, Thursday or Saturday if so you can talk to the guard and enter your Pokemon into the bug catching contest. If you win you get a sun stone, if 2nd place you get a everstone and if 3rd you get a gold berry. Runners up get a regular berry.
put sapphire in the GBA slot of your ds then go to heart gold menu and select migrate from sapphire and pick the Pokemon you want to send then go to the pokepal park and do a catching show (it's in Kanto in Fuhsia city)
no instead they have pal park
By using the pal park in Fuscia city in Kanto
Not long. Just migrate the Pokemon and then go to pal park. Then you enter the catching competition and you catch your migrated Pokemon.