How to get to all the gyms:
1- Falkner (Flying type) - Violet city
2- Bugsy (Bug type) - Azalea town
3- Whitney (Normal type) - Goldenrod city
4- Morty (Ghost Type) - Ecruteak city
5- Chuck (Fighting Type) - Cianwood city
6- Jasmine (Steel type) - Olivine city
7- Pryce (ice type) - Mahogany town
8- Clair (dragon type) - Blackthorn city
9- Lutinet Surge (electric type) - Mermilion city
10- Sabrina (psychic type) - Saffron city
11- Misty (water type)- Cerulean city
12- Erika (grass type) - Celadon city
13- Janine (poison type) - Fuchsia city
14- Brock (rock type) - Pewter city
15- Blaine (fire type) - Cinnabar island
16- Blue (versatile) - Viridian city
No, you don't. You cannot face the Sinnoh Gym Leaders in HeartGold.
different places
You have to beat all of the gym leaders in Johto then look at the map.
Beat all 16 Gym Leaders, then go to Prof. Oak in Pallet Town
Gary (Or blue) is hanging out on Cinnebar Island, but you have to beat all the other Kanto leaders before you can challnge him.
You cannot travel to the Hoenn region in Pokemon Heartgold and Soulsilver.
beat all the gym leaders. Hope this helps!
You need to beat all 16 gym leaders then go to the whirlpool islands
After you beat e4 an all sixteen gym leaders you got to pallet town an talk to proffeser oak he will give you a kanto starter
you beat all 24 jym leaders then beat red at mount silver then go to profeser oaks and heal give u one
You can get all the Pokemon in the cerulean cave where you find celebi below the cerulean cave.
I know that in soul silver, after you beat all 16 gym leaders the professor gives it to you.