Mt. Silver or the Pokemon league
You can defeat the Pokemon League by defeating the Elite Four and the Champion in Pokemon Soul Silver.
In Pokemon Heartgold you need Ho-Oh before going to the Elite Four/Pokemon League so I am sure it's the same for Pokemon Soulsilver.
you have to beat the Pokemon league then go to the Pokemon transfer lab at route 15 you need to go onto ds download play to transfer Pokemon from silver to white but you cannot transfer Pokemon to soul silver
Usually ultra balls are sold in the later cities try blackthorn city or the Pokemon league.
After defeating the Pokemon league,Fly to the bottom of the Pokemon league and enter then walk to the left.
in kanto
Mt. Silver or the Pokemon league
there is no league all you have to do is vs red at mt silver peak but he has Pokemon over lvl 80
You can defeat the Pokemon League by defeating the Elite Four and the Champion in Pokemon Soul Silver.
everything You can do even more in Pokemon Heartgold and Silver
The weakest Pokemon at the Pokemon League are at Level 40. The Strongest Pokemon you'll face is at Level 50.
must obtain the required number of league badges
To enter the Pokemon League, you only need to obtain the eight Johto badges and then find the Pokemon League building.
Pokemon league
On Mt. Silver but first you need all 16 badges and victory on the Pokemon League
The Pokemon League