I only restarted once and I regret it. All my Dream World Points, all my Dream World Pokemon my EV Trained Pokemon that I've had since around 2008, my shiny Charmander who I have never seen again, my Pokemon that had special moves from XD, my Liberty Pass, and all of my GameStop Entei, Raikou, Suicune, and Celebi.
I miss that file.
The only thing I've done differently was use a few different Pokemon and get rid of my starter as soon as I got it's final evolution in my Pokedex.
Oh wow, why did you restart it? :( That sounds terrible tbh.
Either way I've restarted Black a lot (over 11 times probably? I've got a lot of Victini and two playthroughs!) But White, nope, never. It's got all my good stuff on it (plus someone else's stuff lool).