I don't want to GET a Snivy, I merely need to SEE one for my pokedex in white 2. My starter was Tepig, so I've seen all the fire ones, and the water ones from my rival.
No one in White 2 carries a Snivy, so you're out of luck. The best you can do is see Servine at Nimbasa, when you team up to fight the Subway Bosses.
Hope I helped!