I don't remmember very well either, but I do remmember that she took me a whole night to defeat her. Pokémon Silver was my first game of the pokémon series, and the first game that I actually bought for my Red Gameboy Pocket.
When I reached her... well, everything was fine. I was beating every trainer in the Gym, but then... If I'm not mistaken, it was 12am when I got to reach her gym. I was doing a 2nd run, since I didn't know how to get the move "cut" to proceed into the game after the farfetch's quest, or, at least, how to use it. Then I restarted the game, I enjoyed the game, so wasn't painful to restart, after finding out how to make thinks work this time.
About beating her. As I said, after restarting, It was 12am when I finally reached Whitney, but she took me 4hours to beat her. 4am was me super happy, for defeating her! Such great moments of my pokémon life. Sadly, I don't remmember which team I was using. I know that I had chikorita and something.
Trivia: Back then, I always thought that when you lose a battle, is instantly game over, so everytime that I lost to Whitney, I reseted. I never thought that you could grind levels in the wild, or with trainer calls. I fell so dumb now...
Between, I didn't knew anything about english, so it just made everything more difficult.