Seviper cause he hes poison tail and big fangs!!

Out of the games Seviper would most likely win. Alongside having huge fangs, it also has a swordtail, this giving it a clear battle advantage.

In the games however...Arbok will butcher Seviper. Since it's faster, it can OHKO it with Earthquake, and even if it doesn't it won't be OHKOed by Seviper's own Earthquake either thanks to its Intimidate. Unless, of course, the Seviper scores a critical hit. Damn hax.

But putting that little lesson aside, I'm rooting for the Seviper. =D