different places
No, you don't. You cannot face the Sinnoh Gym Leaders in HeartGold.
All of them have phone numbers, but there are certain ways to get them. I would try looking up "how to get all gym leader's phone numbers in heartgold" on google
You have to beat all of the gym leaders in Johto then look at the map.
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
you beat them in a battle
You get the HM Rock Climb from Prof. Oak when you beat all the gym leaders in both regions.
you have to go to every gym in kanto a beat all the gym leaders
I know that in soul silver, after you beat all 16 gym leaders the professor gives it to you.
You can get all sixteen badges by defeating all eight Johto gym leaders, defeating the Elite 4, and then beating all eight Kanto gym leaders.
you have to beat all 8 gym leaders in joto before you can go to victory road