You have to as it is a main part of the storyline.
First, you have to get through Victory Road. Before you can exit Victory Road, Rival will challenge you to a battle. After you defeat him (if you do defeat him) you can exit Victory Road and enter the Pokemon League. Then you defeat the Elite Four and Champion.
i think he goes to blackthorn, and inside dragons den, after that you can challenge him before entering the Pokemon league
Route 208 (you get a Carbos from the ground), Route 210 (you get a Wave Incense), Mt Coronet (don't remember what you get), and Pokemon League (you get to challenge the Pokemon League).
Beat the Pokemon league and fill the pokedex. Raise a team, and challenge all of your friends to be the best.
Same as it is in every Pokemon Game in existance: Challenge and Defeat all the gym leaders, defeat whatever villianous group is active, then travel up Victory Road to get to the Pokemon League. Challenge them. WIN! =]
You go to sunyshore city and challenge the gym there. After you beat it, you can go to the pokemon league.
No
After you beat the Pokemon league, you can train all your Pokemon, challenge the battle tower, do both, or start over.( i don't recommend starting over)
No. You need to go to the Pokemon league before you can catch it.
Nope
Many people think that after you beat the Pokemon league and your rival, you completed the game. To finish the game totally, get every Pokemon in the kanto and national pokedex and beat the Pokemon league. It's a real challenge!
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.