Where can you re-challenge gym leaders in heartgold and soulsilver?

Answer 1

You can rechallenge all 16 Gym Leaders in the Fighting Dojo in Saffron City however you need to first register their phone numbers and then call them on a specific day in order to rematch them then they'll be in the Fighting Dojo until you battle them.

You can register Falkner's number by talking to him on the 4th floor of the Celadon Department Store on Mondays, he'll accept rematches on Saturday mornings.

You can register Bugsy's number by talking to him in Viridian Forest on Thursdays, he'll accept rematches on Thursday afternoon.

You can get Whitney's number by talking to her on the 6th floor of the Goldenrod Department Store any day between noon and 4 PM, she accepts rematches on Saturday mornings.

You can get Morty's number by talking to him in the Bellchime Trail on Mondays and Tuesdays, he'll accept rematches on Tuesday nights.

You can get Chuck's number by talking to his wife who is the same lady to gave you the Fly HM, he accepts rematches on Wednesday nights.

You can get Jasmine's number by talking to her in the café in Olivine City between 1 PM and 2 PM on any day, she accepts rematches on Wednesday afternoons.

You can get Pryce's number by talking to him any day between 6 AM and 10 AM at the Lake of Rage, he accepts rematches on Monday morning.

For Clair's number, you have to battle your Rival at Mt. Moon and then you have to battle with your Rival against Clair and Lance in Dragon's Den and then you can get Clair's number any day between 6 AM and 10 AM by talking to her in Dragon's Den and she'll accept rematches on Friday nights.

For Brock, you can get his number in Diglett's Cave any day between noon and 3 PM and he accepts rematches on Saturday nights.

For Misty, you first have to defeat or catch Suicune and then you can talk to her any day between 4 PM and 6 PM and she'll accept rematches on Wednesday mornings.

For Lt. Surge, you have to battle or defeat Zapdos and then he (Lt. Surge) will be outside of the Power Plant any day between 9 AM and noon and he'll ask for you to show him a Pikachu. After showing him a Pikachu he'll give you his number and he'll accept rematches on Friday mornings.

For Erika, you can talk to her on Saturdays and Sundays between 3pm and 5pm in Celadon City in order to get her number and she'll accept rematches on Sunday afternoon.

For Janine, you can get her number any day between 4 PM and 6 PM at the Reception Gate to the Victory Road and she'll accept rematches anytime during the day on Monday.

For Sabrina, you can get her number by talking to her on the Olivine Harbor Deck anytime on Friday, she'll accept rematches on Sunday afternoons.

For Blaine, you can get his number by talking to him on Tuesdays on Cinnabar Island and he'll accept rematches on Tuesday afternoons.

For Blue, you first have to have Daisy Oak massage your Pokémon 5 times and then you have to show her a Pokémon that has maximum happiness, once you do she'll give you Blue's number and then you can call him for a rematch on Sunday nights.