Yes it is. I encountered this before, but I was successful (thank goodness). There will also be a horde of Zangoose attacking a lonely Serviper in Pokemon X. As I heard, you can't face Serviper alone in Pokemon X and Zangoose alone in Pokemon Y. --- Crap, I edit a lot. Sometimes even serious times have their funny moments: http://puu.sh/2Su65
yup i watched it happen in my game, only i managed to take out the seviper and then caught the zangoose. good thing tc they do show up solo.
also i heard about someone that had the same thing happen but the zangoose was shiny. went the same way as tc described. --- .....said an almost 30 year old married guy driving a van part time for a living 3ds my fc, 0602-6823-9646, my wifes 0146.9112.0071