Arbok

Intimidate
Lowers the foe's Attack 1 stage. Decreases wild encounter rate.
Shed Skin
30% chance to heal status.
Tier: UU
Statistics
Min- Min Max Max+
HP
60
- 261 324 -
Atk
85
185 206 269 295
Def
69
156 174 237 260
SpA
65
149 166 229 251
SpD
79
174 194 257 282
Spe
80
176 196 259 284
Name Item Ability Nature

Physical Attacker

Choice Band / Life Orb Intimidate Jolly
Moveset EVs
~ Gunk Shot
~ Earthquake
~ Crunch
~ Ice Fang
56 HP / 252 Atk / 200 Spe

A souped up Gunk Shot is really quite scary (if it hits), and Earthquake provides excellent type coverage. With these EVs, Arbok hits 270 Speed, beating neutral Gligar and Jolly Solrock. Ice Fang is here predominantly for the former and Crunch is for the latter.

Name Item Ability Nature

Double Status

Leftovers Shed Skin Impish
Moveset EVs
~ Gunk Shot
~ Glare
~ Stockpile
~ Rest
252 HP / 252 Def / 4 SpD

This is really a novelty. Glare offers general paralysis support while Gunk Shot has a 30% poison side effect. Rest works all right since you might wake up early with Shed Skin.

Other Options

Giga Drain, Poison Jab (for reliability), Glare, Fire Fang, Thunder Fang, and Rock Slide are all alternatives in slot 3 and 4 on the first moveset. From the list, Giga Drain (with a Naive nature) is probably the most useful for Pokémon with a Grass quad weakness—Gastrodon, Whiscash, and Quagsire in particular—who are likely to be default switch-ins.

EVs

You could move a few HP EVs into Speed to outspeed further Pokemon in the first set.

For the second set, if you want Arbok to take special hits better, you can move EVs from Defense into Special Defense. In particular, 144 EVs in Defense and 112 EVs in Special Defense (with 252 EVs in HP) gives Arbok maximum defenses from both approaches.

Opinion

Arbok is really a one trick pony... snake. Use the physical attacking moveset or use another Pokémon. It does not fit any other role adequately. Intimidate is a handy ability, but forgettable Defense and HP undermine it. However, it can switch in to the odd physical Fighting, Poison, or Bug attack.

Counters

Solrock and Gligar are decent Pokémon to switch to in a pinch, brushing off 3 out of 4 of Arbok's attacks each. However, you need to be very wary of that fourth attack! All of the Water/Ground Pokémon are excellent counters, but you may occasionally suffer a random Giga Drain.