Arbok is an extremely underrated Pokemon. It has the ability to absolutely TEAR offensive teams apart. It's quite bulky with Intimidate and Coil, and has great coverage, yet it sits in PU right now. I, for one, find this unacceptable as it is such a beast when used correctly.
Unfortunately, it cannot function well in the higher tiers, but it is an incredible Pokemon in NU who deserves waaaay more love than it is given.