Urm... the region where you start
In the Game Corner in Johto, if you earned enough Game Coins.
heart gold, soul silver, and crystal(old)
Ask Ketchum's video game counterpart is in Pokemon Heart Gold and Soul Silver on the peak of Mt. Silver in Johto. He will be waiting there for you to battle him.
Gold, silver, and crystal all begin in Johto. This is true, however they are all GbC (gameboy color) games, and will not work on a phone's gba emulator.
You have to beat 16 gym leaders and beat elite 4 in kanto and johto to beat the game.
this is only possible in pokemon gold/silver/crystal/heart-gold/soul-silver, after you've beaten the elite four and the champion.
once you finsh the sappfire game you can go lab and get the johto Pokemon to start the johto league now and train them to beat the johto league
OK I'm going to improve the answer to this question because the guy before me wants to be an a#$ about it. I don't think you can catch Pokemon from Johto in Pokemon Diamond or Pearl, but I do know they are coming out with a remake of Pokemon Silver, Gold, and Crystal. It is for the DS so you will have to trade between someone with a Silver, Gold, or Crystal version to your Diamond and Pearl game.
no you can not go to johto reigon on Pokemon red the only game that i know that you can go to johto is gold,silverand crystal version
in every game except gold and silver and crystal there are 8 badges, gold silver and crystal have 16 cause you can fight the kanto and johto leaders.
you have to beat every trainer in the game (including the elete 4 and champion)
you can't. because the game it self (crystal,silver,gold) is a different size then the ds gba game holder BUT you can trade Pokemon from the johto region to Pokemon firered,leaf green, ruby, emerald, Sapphire THEN you can migrate to dimond/pearl but to do this you need 2 gameboy advance SP games.HOPE THIS HELP :)