in the cities
you need to beat all the gym leaders johto and kanto
in seafoam islands in kanto or mahogany in johto
cianwood city.
you have to get all 16 gym badges
the 15th gym leader in soul sliver is blaine and he uses only fire type pokemon
the sexth gym leader jasmine is in the lighthouse
beat the last gym leader on soul silver in johto
you have to surf to Cianwood city and go to the pharmacy right beside the Pokemon center. Then beat the Gym to get HM02 - Fly
you battle them in the dance center after you defeat Claire, the last gym leader in johto
Beat all the Johto gym leaders and the Kimono Girls. (They're in Ecuteark city.)
The 5th gym leader in Johto is Chuck. He is located in Cianwood City.
Defeat all of the Johto and kanto Gym Leader, talk to Prof. Oak, and he will let you go there and challenge red