you have to go to Goldenrod and visit the lady with the flowers. She will then give you special water to use on the sudowodo ;) the head north for eucretek city
First, you must have all 7 other Kanto badges. Go to Cinnabar Island and talk to Blue, the only guy standing there. He will then go to the Viridian Gym, where it will now be open.
you have to have 7 kanto gym badges then find blue at cinnabar island
Not enough info: which gym leader?
you have to go to every gym in kanto a beat all the gym leaders
misty
Get all gym badges of Johto and defeat the Pokemon league. Then you have access to the Kanto Region.
You can access Cerulean Cave in SoulSilver after you get all 16 gym badges (Johto and Kanto).
route 2 in Soulsilver is in Kanto. the second region of the game... once you have gotten all of Johto's badges you can go to Kanto and defeat all of those gym leaders and then you can go to route 2...! hope I've helped. ~Amelia age 6~
His name is Blue, and he is on Cinnabar Island. Show him the other 7 Kanto Badges and he will go to the Viridian City gym. Then, go to Viridian City and battle him at that gym.
In HeartGold and SoulSilver, yes, you will be able to go to Kanto and travel mostly its entire region which includes battling the Kanto Gym Leaders, but first the Elite Four. After, you've gotten all 8 Johto badges, talk to Prof. Elm and he'll give you a ticket to S.S. Aqua, which will take you to Kanto.
beat the first 7 gym leaders of johto (assuming that you've already got the 8 first gym badges in kanto)
HeartGold/SoulSilver-Viridian City. You have to have the other 7 kanto badges and then find him on Seafoam islands. He will go back to the gym in Viridian and you can fight him.