no only once
No.
You cannot re-battle the Gym Leaders in Pokémon Black and White.
nope
no you cannot but you can battle latias/latios
sorry but no
no there is not
no
battle wild pokemon until yours is lvl18+
well you can battle the champion from another region in undella town (first house to the left)
The Champion in Pokemon Black and White is only after you have defeated N and Ghetsis For the final time. Then the second time you battle the Elite Four/Pokemon League, You will battle Champion Alder. All his Pokemon are Lv 75.
You cannot battle between a Pokemon Black game and a Pokemon Soulsilver game.
Okay. insructions: 1) upgrade your Pokemon black/white to version 1.2.0 2) talk to Cynthia in undella town 3) Go to the gyms and battle away :)