Pokemon white 2 hack or glitch?

I bought a pokemon white 2 game a while back. I let it sit in my closet for a while before playing it. When i took it out to play the other day it was acting stupid. It was all normal at first, i chose my starter as snivy. I caught some purlions and a pidove. Everything was fine until i entered the 2nd gym. Instead of roxy having white hair she had black hair. I didn't think much of it since it was a used game plus i didn't know if she only had white hair in the show. So i tried 3 or 4 times to defeat her. Each time i lost. But when i tried the 5th time when i got back to the pokemon center after all my pokemon had fainted i notice one of my purlions were gone. I was really upset since it was my very first purlion. But there was really nothing i could do to get it back. So i noticed each time i would loose to her i would loose a pokemon. I tried to find out a way to get them back but found nothing. So i was down to my last pokemon, my starter. Snivy. So i went back to the gym hoping i would beat her and get my pokemon back but, when i did beat her snivy was gone too! I had no pokemon left and it wouldn't let me use poke balls. Odd enough, i didn't run into any wild pokemon or trainers. when i got to the next gym it was empty all there was was a sign outside saying "Snivy is here." I was very confused and figured some idiot had hacked my game. So i looked all over for my beloved pokemon but found nothing. So i decided to move on.

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