In Pokémon SoulSilver, the Pokémon League Champion Lance has a level 46 Gyarados, a level 48 Charizard, 3 Dragonites which are at level 49, 49 and 50 and a Level 48 Aerodactyl.
In the indigo platue
normally, he is the elite 4 champion.
The Elite Four Champion in Pokémon SoulSilver Version is Champion Lance.
You can defeat the Pokemon League by defeating the Elite Four and the Champion in Pokemon Soul Silver.
Lance, the Dragon-Type master is the champion of the Elite Four. Red can also be battled at Mt. Silver, but he is much stronger than Lance.
if you defeated the elite four and champion you can see him in at indigo plateu (pokemon league)
It might depend on the Pokemon, though usually you can face legendary Pokemon again if you beat the Champion.
Mt. Silver is near Victory Road. You have to defeat the champion first to go to the left in the entrance. Then you can come to Mt. Silver.
psychic poison fighting dark champion dragon
unfortunately, no. At the present time, there is no way to battle the Hohenn Champion.
you should have an ice type Pokemon, a fighting type Pokemon and an electric type Pokemon
this is only possible in pokemon gold/silver/crystal/heart-gold/soul-silver, after you've beaten the elite four and the champion.