Ekans can be found in the following areas in Silver/Crystal: Routes 3, 4, 32, 33, 42 (Crystal only), and via Headbutt (Crystal only). In Gold, it can be purchased for 700C in the Goldenrod Game Corner. In Silver/Crystal, Arbok can be found on Routes 3, 4, 26, 27, 28 (Crystal only), 42 (Crystal only), and Mt. Silver (Crystal only).
Sporting a solid mono-Poison typing, a pretty decent Attack and Speed, and a very good offensive movepool, Ekans is a decent 'mon to use in any Johto run. While Arbok's 60/69/79 defensive stats are not exactly ideal, it still has the ability to outlast a good portion of opponents by using its very spammable Sludge Bomb, a strong STAB attack of which many GSC Pokemon are jealous. In addition to a strong STAB attack with a 30% chance of poisoning, the Ekans line also has at its disposal very useful coverage moves in Earthquake, Return and Bite, as well as handy support moves in Screech and Glare. With only two weaknesses, strong attacks, and an extremely important inability to be poisoned, Ekans can make virtually any team better.
Gym #2 - Bugsy (Azalea Town, Bug-type): Ekans has an easy time defeating both the Metapod and Kakuna, especially since you can't be poisoned. The Scyther, though, is a different story: Unless you overgrind to level 23 and taught Ekans Glare, there is nothing you can do to stop Scyther from slowly but surely steamrolling through your entire team with Fury Cutter.
Rival (Azalea Town): With Bite, Ekans does a superb job in this fight. Gastly and Zubat will go down with a few Bites, although be wary of their respective status moves. Against Bayleef, Ekans should be able to outstall it by spamming Poison Sting, which has a relatively high 30% chance of poison. Bayleef, meanwhile, can only use Razor Leaf in return. Croconaw and Quilava are much tougher for Ekans, although you can try to fish for a Poison Sting poison while tanking a couple of Water Guns or Embers.
Gym #3 - Whitney (Goldenrod City, Normal-type): Her lead, Clefairy, can be handled by a combination of Bite and Dig. Since you only have two weaknesses, the odds of Clefairy doing significant damage to you with a Metronomed attack are relatively slim. Nonetheless, you definitely want to kill it as soon as possible. Miltank, Whitney's other, overall much more dangerous 'mon, can and will steamroll through your whole team if you don't play your cards right. The best thing you can do is fish for a poison with Poison Sting. Thankfully, unlike the Bugsy fight, you now have access to Dig, which gives you a chance to outstall Miltank by using Dig whenever it tries to use Rollout. That way, she can never continue to use Rollout and sweep your team. Ultimately, though, if you want to KO Miltank quickly, then you'd best use something other than Arbok.
Rival (Burned Tower): Arbok does very well in this fight. Haunter can be taken down with either Bite or Dig. Just be wary that if you decide to use Dig, Haunter can put a Curse on you even while you are underground. Magnemite is easily taken out with Dig. Bite the Zubat as before, but watch out for its newly-acquired Confuse Ray. Arbok easily takes out Bayleef after a few turns. You can easily 2HKO the Quilava with Dig, while Ember won't be doing a lot of damage at this point. For Croconaw, it will have a tough time dealing significant damage with Water Gun, so you can probably wear it down after a few turns.
Gym #4 - Morty (Ecruteak City, Ghost-type): Against his Gastly and his level 21 Haunter, it is recommened you use Bite since they both can use Curse. Against the level 23 Haunter, you are probably going to want to use Dig since it has Spite. Finally, whatever you do, do not let yourself get put to sleep from Gengar, since from there it will easily OHKO you with Dream Eater. Your best bet is to spam Dig like no tomorrow and hope that Hypnosis misses.
Eusine (Cianwood City, Crystal only): The Drowzee has access to Confusion, and while it probably won't OHKO you outright, it is best to let a teammate handle this matchup. His Haunter has the Mean Look + Hypnosis + Curse combo, but thankfully it can only use one of those moves at a time, so you should be good there. Finally, you can use Dig with some success against his Electrode, but beware that it can and will spam Thunder.
Gym #5 - Chuck (Cianwood City, Fighting-type): If you already completed the Rocket Hideout quest and thus have access to the TM Sludge Bomb, then this fight shouldn't be that bad. Premeape goes down in two hits at worst, while it can't really do anything back to you. Poliwrath is a lot bulkier and can potentially 3HKO you with STAB Surf; however, you will outspeed and deal a significant amount of damage with Sludge Bomb. You may have to use an Awakening or a Lemonade, but Arbok should definitely come out on top here.
Gym #6 - Jasmine (Olivine City, Steel-type): The fall Magnemites easily fall to Dig. Steelix is extremely bulky on the physical side and resists your lone special move. Its Iron Tail, while inaccurate, will severely dent Arbok if not outright 2HKO. It is feasible to use a Screech(x2) + Dig strat here, but it is best to leave this matchup to a special attacker.
Rocket Executive battle #1 (Team Rocket HQ): The Zubat will be pretty annoying if you don't manage to flinch with Bite/Headbutt. The Koffing, though, is far more dangerous as it can ruin your day with Selfdestruct. Worse yet, Dig might not even OHKO Koffing since it has pretty decent bulk. Bite + Dig is probably your best bet. You should be able to outdamage the Raticate just fine, although be wary of Hyper Fang.
Rocket Executive battle #2 (Team Rocket HQ): This fight should not be a problem at all. Just use Dig against the oppsosing Arbok and use your Normal coverage move of choice against the Gloom and Murkrow (since you will have not gotten Sludge Bomb yet).
Gym #7 - Pryce (Mahogany Town, Ice-type): Both the Seel and Dewgong will attempt to outstall with Rest, so Screech will be very effective here. After a Screech, you shouldn't have any problem OHKOing and 2HKOing the Seel and Dewgong, respectively. The Poliswine, meanwhile, resists your STAB, but the strongest attack it can use against you is an inaccurate Blizzard coming off of a paltry 60 base special attack. Screech + Normal type attack will work best in this case.
Rocket Executive battle #3 (Goldenrod Radio Tower): This fight is very dangerous as every single one of his mons can potentially OHKO Arbok with an exploding move. If you want to survive, you are going to want to KO his mons ASAP so that they will have a lower chance of going boom. Bite + Dig should be enough to take out the Koffings. The Weezing, however, is immensely bulky and is packing Explosion, so you are definitely going to want to use a Rock, Steel or Ghost-type for this matchup if you have one.
Rival (Goldenrod Underground): Not a whole lot has changed for this fight, except for the fact that you now can nuke all three possible starters with Sludge Bomb. Also, he has acquired a Sneasel, which you can also hit really hard with Sludge Bomb if not OHKO outright. For his remaining three mons, keep doing whatever you did in the previous fights: Normal attack against Golbat, Dig against Haunter, and Dig against Magnemite.
Rocket Executive battle #4 (Goldenrod Radio Tower): The opposing Arbok can only hope to paraflinch with Glare + Bite, whereas you can simply 2HKO with Dig. Vileplume may tank a couple of Sludge Bombs, but since you resist both its STABS, it can only really slow you down with Sleep Powder. Murkrow should easily fall to a couple of Sludge Bombs while dealing 32 HP damage in return with Night Shade.
Rocket Executive battle #5 (Goldenrod Radio Tower): Sludge Bomb deals a significant amount of damage against Houndor, probably OHKOing it outright. His Koffing, thankfully, does NOT have an exploding move, so you're free to use Headbutt/Bite + Dig as usual. Technically Houndoom's base speed is higher than that of Arbok, but because you will have gained so much Stat Experience by this point, you have a legitimate shot of outspeeding and 2HKOing with Sludge Bomb without too much trouble.
Suicune (Bell Tower, Crystal only): Arbok fares well enough here, thanks to its being a tank and Suicune also being one. While Suicune can set up the annoying Rain Dance + BubbleBeam combo, Arbok's Sludge Bomb will be as strong as that right from the start, and may poison Suicune, helping you defeat it.
Gym #8 - Clair (Blackthorn City, Dragon-type): None of her three Dragonairs will be able to do any sort of significant damage to you, while you in turn should be able to 2HKO them with Sludge Bomb. However, they will make it their mission to cripple you with Thunder Wave. A paralyzed Arbok will not fare well at all against the behemoth that is Kingdra, which will further cripple you with Smokescreen and then spam Surf. A healthy Arbok, on the other hand, will be able to outspeed Kingdra and potentially 3HKO with Sludge Bomb, although it may be worthwhile to use Screech beforehand so that Clair doesn't get a chance to heal.
Rival (Victory Road): Sneasel, his new lead, will easily fall to a Sludge Bomb or two without dealing any sort of significant damage in return. If you have Earthquake, then it will be even easier to elimate Haunter, Magneton and Typhlosion. Meganium and Feraligatr fall to Sludge Bomb as usual; although you probably won't be able to OHKO them, you will definitely outlast them provided you are at full health. For his sixth 'mon, Silver has picked up a Kadabra, which has the potential to deal a lot of damage to Arbok. If, however, you've grinded Arbok to the low 40s, then it should be able to outspeed and OHKO with Sludge Bomb without any problems.
Elite Four Will (Indigo Plateau, Psychic-type): Every single one of Will's 'mons knows Psychic, so sending Arbok out willy-nilly is a good way to get it killed. If you really feel you need to use Arbok for this fight, you should probably grind it to [i]at least[/i] level 45 so that it can reliably 2HKO everything but Slowbro with Sludge Bomb. Even then, any critical hit Psychic from any of Will's 'mons will surely OHKO you, so just be very, very careful.
Elite Four Koga (Indigo Plateau, Poison-type): All of Koga's team resists your STAB, so this is where Arbok solid coverage moves come into play. You definitely want to KO his Ariados right away with Earthquake/Return lest it troll you with Double Team and Baton Pass away. Muk gets easily 2HKO'd by Earthquake, although it will attempt to annoy you with Acid Armor and Double Team. Forretress is a very dangerous matchup as it is extremely bulky physically and has access to Explosion, which will easily OHKO Arbok, so let a special attacker take care of this. The Venemoth is somewhat threatening in that it does know Psychic, but you shouldn't have a problem tanking a couple unSTAB'd Psychics and dealing hard damage in return with Return or Earthquake. Finally, Crobat can harass you and Double Team and chip away at your health with Wing Attack, but thankfully it does not have any Confusion-inducing moves. Three or four Returns should do the trick just fine.
Elite Four Bruno (Indigo Plateau, Fighting-type): This is definitely Arbok's easiest fight of the E4. The Hitmontop can use Dig, but in this generation Earthquake deals twice as much damage to an underground foe, so make sure to abuse that mechanic. Neither Hitmonlee nor Hitmonchan can deal any significant damage to you, but keep in mind that Lee can use Swagger. Onix will surely tank an Earthquake and retaliate with Earthquake in return, so you should probably let a Grass or Water-type take care of it if at all possible. The best thing that Machamp can do to hurt you is a critical hit Cross Chop, but it will not come anywhere close to OHKOing you Meanwhile, you can potentially 3HKO it with Sludge Bomb, especially if you manage to poison it. (Remember, Guts does not yet exist, so you don't have to worry about that.)
Elite Four Karen (Indigo Plateau, Dark-type): Umbreon is insanely bulky and will annoy the crap out of you with Confuse Ray and Sand Attack. The best thing you can do is use Screech and then spam Sludge Bomb like no tomorrow, hopefully landing some poison in the process. Vileplume and Murkrow both fall to Sludge Bomb without too much trouble, although Vileplume can potentially paralyze you with Stun Spore. Earthquake the Gengar into oblivion, but watch out for Curse and Destiny Bond. (Keep in mind, though, that Gengar will never, ever, use Destiny Bond first turn, so you should be good there.) How Arbok fares against the Houndoom is largely dependent upon your level and stat experience. What will probably happen is that you will end up outspeeding and 2HKOing with Earthquake. Just know that its Flamethrower will be a solid 3HKO on you, if not 2HKO.
Champion Lance (Indigo Plateau, Flying-type): Depending upon Arbok's level and your ruleset regarding healing items, Arbok can hold its own in this fight and then some. None of Lance's 'mons has any supereffective move against Arbok, but they all do carry Hyper Beam, which can easily KO a weakened Arbok. They are also all pretty dang bulky, so it's going to take a handful of Sludge Bombs to deal good damage.
From this point onwards, you can fight the gyms in any order, though you will need to retrieve the Machine Parts from the Cerulean City gym before you have access to the earlier portion of Kanto. Feel free to anticipate or postpone any battles as needed.
Gym #9 - Brock (Pewter City, Rock-type): Simply spam Earthquake and win. Both his Graveler and Rhyhorn have Earthquake, but because they are NFE's and you will be at least ten levels higher by this point, you shouldn't have any problems at all.
Rival (Mt. Moon, optional): Be more careful around Gengar, if you aren't higher leveled enough to outspeed, just in case it uses Destiny Bond. Otherwise, Earthquake is the way to go. Sludge Bomb and Earthquake together can dispose of everything like last time, but Alakazam must now be avoided unless you have a preposterous level advantage.
Gym #10 - Misty (Cerulean City, Water-type): Sludge Bomb everything except for the Quagsire, which can be most efficiently dealt with by Screech + Earthquake.
Gym #11 - Lt. Surge (Vermilion City, Electric-type): Spam Earthquake and win. His Electrodes both have Explosion, but they are only at level 40, you should be at a high enough level to outspeed and OHKO them.
Gym #12 - Erika (Celadon City, Grass-type): STAB Sludge Bomb will destroy everything in this gym.
Gym #13 - Janine (Fuchsia City, Poison-type): Everything in this gym is under level 40, so you should have no problems outspeeding and OHKOing everything with the appropriate coverage move.
Gym #14 - Sabrina (Saffron City, Psychic-type): If, somehow, your Arbok is below level 50 by this point, you probably shouldn't attempt this fight. If, however, you are in your mid-50s, then you should be able to outspeed and OHKO everything with Sludge Bomb. Still a risk, though, and not worth taking if you have better options; Arbok's Attack isn't THAT outstanding.
Gym #16 - Blue (Viridian City): Abork can defeat the Pidgeot without too much trouble. You should definitely avoid his Alakazam and Rhydon, as the former can outspeed and OHKO you with Psychic and the latter can tank your Earthquake and retaliate with a much more powerful Earthquake of its own. The Gyarados can deal major damage to you with Hyper Beam, but you will outspeed and probably 2HKO with Sludge Bomb. The Exeggutor will be easily 2HKO'd by Sludge Bomb if not OHKO'd outright. If that Exeggutor manages to set up Sunny Day before dying, then this makes Arcanine all the more dangerous. Your Earthquake should be able to 2HKO it just fine, but please don't forget that Arcanine has a strong priority attack in Extremespeed, which can pick off a weakened Arbok.
Rival (Indigo Plateau, optional): This fight is a repetition of what already happened in Victory Road and Mt. Moon. The only difference is Golbat being a Crobat, but still approachable. Pack Sludge Bomb, Earthquake, and another move to deal with Crobat unless you want to leave it to another teammate, and Arbok will be fine. Avoid Alakazam, again.
Red (Mt. Silver): Assuming you are in the mid-70s by this point, Pikachu falls to an Earthquake easily. (Due to your high amount of stat experience by this point, you should have no problems outspeeding.) Espeon will destroy you with STAB Psychic, so avoid that. Against Snorlax, you can use the historically useful strategy of Screech + Sludge Bomb, which will throw off its Rest cycles. Just know that its Body Slam will hurt you bad and potentially paralyze. Venusaur cannot deal any significant damage while you Sludge Bomb to your heart's content. Both Charizard and Blastoise can hit your hard with Flamethrower and Surf, respectively, but you can smack them around with Sludge Bomb and fish for the poison.
Like many Pokemon in this generation, Ekans' level up movepool leaves something to be desired. The snake starts off with Wrap and then at level 9 learns Poison Sting. These moves can potentially wear down the opponent over time, but unfortunately will not ultimately do a whole lot of damage. At level 15, Ekans learns Bite, whose flinch rate can be rather useful, especially when combined with Glare, which Arbok learns at level 25. Just remember that Glare in this generation only has 75% accuracy, which can let you down. Screech, at level 32, is rather useful in that it softens up some of the many walls that Arbok wants to break.
Arbok's TM movepool is very good. If you want a flinch-inducing move coming off of Ekans' higher attacking stat, then go with Headbutt. Curse, Toxic, Giga Drain and Protect would be great moves for Arbok, but unfortunately all of these TMs come post-Elite Four. Arbok makes a fantastic user of Earthquake, which is easily its most important coverage move. In the same way, Dig is a great move in the early- to mid-game. Return is a great coverage move for any physical attacker due to its incredibly high BP at max happiness, but you may have teammtes who want that move much more badly. By far Arbok's most important move is Sludge Bomb, the TM for which you need to get ASAP in order to maximize Arbok's effectiveness. Finally, Strength is a mighty fine option in this generation that does not require any sort of competition unlike Return.
Minimum stats are calculated with 0 EVs, IVs of 0, and a hindering nature, if applicable.
Maximum stats are calculated with 252 EVs, IVs of 31, and a helpful nature, if applicable.
Ekans Line Ratings
At what point in the game should I be evolved? If you want to use it against Whitney, then you should definitely have an Arbok by then. Otherwise, you should be fine with evolving around the time of Morty.
How good is the Ekans line in a Nuzlocke? Pretty damn solid. This is the only generation in which it gets STAB Sludge Bomb coming off of its higher attacking stat. Arbok's niche as a speedy physical attacker with a great defensive typing is a rather valuable role here in generation II Johto.
Weaknesses: Psychic, Ground
Resistances: Grass, Fighting, Poison, Bug
Neutralities: Normal, Rock, Dark, Steel, Ghost, Dragon, Fire, Flying, Ice, Water, Electric