How to get through the vermilion city gym?

Ground-type Pokémon are at a definite advantage here, although Grass-type Pokémon have a built-in resistance to Electric-type moves, so they can also do fairly well. Diglett is a decent Pokémon to use against the Gym, provided you’ve leveled it up a little bit, since it is a pure Ground-type — Rock/Ground-type Pokémon may run into some difficulty with one of the Gym Leader’s Pokémon.

In order to get to the Gym Leader, you’re going to need to activate two switches to deactivate the electric barrier in the back of the Gym.

The Trainers in the Gym are all technically optional, but you might as well fight them to gain some money and experience.

The first of the switches is to the right of the blue trash can. You can find the second switch directly above the first switch. That will open up the way to Lt. Surge, the Gym Leader.

All of the Pokémon on his team use the very powerful Thunderbolt — a Special-based Electric-type move with a solid 90 power and a chance of paralyzing you. They all will get STAB from Thunderbolt as well, meaning it will hit extra hard.

His first Pokémon, Voltorb, knows Swift and Light Screen in addition to Thunderbolt. Light Screen will half the damage Lt. Surge’s Pokémon take from Special-based moves for the next five turns, while Swift will hit for a reasonable amount of damage to anything looking to avoid Thunderbolt. Thunderbolt hurts, though, even against Pokémon that resist it.

Magnemite is an Electric/Steel-type, meaning it resists a lot of types, but in this case it’s actually to your advantage since it has a huge weakness to Ground while also being weak to Fire and Fighting. It has just Thunderbolt and Sonic Boom, the latter of which hitting for exactly 20 damage and easily taking down most of your Pokémon in just three hits, which is a definite threat for any Ground-type you were considering using, especially Diglett, which has very low HP. Magnemite also has a lot of Special Attack, so it will hit quite hard with its Thunderbolts, capable of doing nearly half of an evolved Pokémon’s HP, even with 50+ Special Defense. Partner Pikachu with Dig or partner Eevee with Sizzly Slide or Dig should take it down without much issue, though, and both have the defenses to take a Thunderbolt or two.

Lastly is his star Pokémon: Raichu. This thing is very fast, packs Thunderbolt, Quick Attack, and Double Kick. Double Kick means the likes of Geodude aren’t able to completely shut it down, although Geodude’s defenses mean it can take a Double Kick or two.

If you have a Grass-type Pokémon, you can use it to fight fairly well against Raichu. Putting it to sleep with Sleep Powder is a good first step, then follow up with Razor Leaf, Mega Drain, or Leech Seed, depending on which Pokémon you’re using. Ivysaur, Gloom, and Weepinbell also all resist Double Kick, so the most you’ll have to deal with is Raichu’s Thunderbolt, which you resist. An X Sp. Def can be used to assure survivability from everything but a critical hit, too.

If you’re playing Let’s Go, Pikachu, your Pikachu resists Thunderbolt and can use Dig to deal a lot of damage to Raichu. Eevee in Let’s Go, Eevee is also a possibility, but the problem is it doesn’t resist Thunderbolt and is weak to Double Kick, making it a worse option, even if it uses Dig — however, you can burn Raichu with Sizzly Slide to stop it from using Double Kick.

After defeating Lt. Surge, he’ll reward you with the Thunder Badge, a badge that increases the level traded Pokémon will obey you by 10, so up to 40 for your third Gym Badge. He’ll give you his own Autograph, a Key Item without much of an effect. Lastly, he’ll give you TM36 Thunderbolt, a very powerful Electric-type move that you probably got to see first-hand, unless you used Diglett, Geodude, or Onix.

Shake your Joy-Con to see another victory scene with your partner Pokémon.

Upon leaving the Gym and chopping down the small tree, you’ll see Misty by the Poké Mart. She’ll heal up your Pokémon to full health and will also tell you to check out Diglett’s Cave, teleporting you straight there if you allow her to.

If you haven’t already checked out Route 11, now might be a good time to, otherwise you can head into Diglett’s Cave to return to the earlier routes and also get a helpful — but optional — Secret Technique.

Lastly, after earning your third Gym Badge, new items will be available for you in the Poké Mart.

The newest additions are:

Vermilion City is the first stop for the luxury liner S.S. Anne, now on its annual Pokémon cruise. It's full of rival trainers, but for now keep focused on a few interesting pleasures in the city itself, including the chance to get a Bike Voucher! Then, after you finish on the ship, return here to challenge the shocking local Gym Leader, Lt. Surge.

The trader won't deal with Yellow players, but they can talk to the policewoman just outside for a free Squirtle once they've won the Thunder Badge. She is hoping that you will take good care of it. It's only Level 10, so it'll take a while to train, but you won't get many other Water-types for a while. With the trainers at Route 11 and the Digletts at Diglett's Cave however, it can catch up with the rest of this game's Pokémon levels quickly.

Red and Blue players can trade a Spearow for a one-of-a-kind Farfetch'd in the building above and to the right of the Gym. Don't hesitate to make this trade if you have an extra Spearow! If you don't have a Spearow to spare, you'll get a chance to grab one in the upcoming Route #11. Farfetch'd isn't really a good in-game Pokémon to be honest but it can be useful as a HM slave and can learn the Cut, an HM move which will be needed after the S.S Anne.

Convince the man in the building west of the Pokémon Center that you love fishing as much as he does and he'll take a shine to you. He will give you his Old Rod as a gift! Now you can use it near any body of water and get... a Magikarp. Or... another Magikarp. Yes, that's all this rod catches. You could have saved 500 if you didn't buy one from the Mt. Moon Pokémon Center earlier, wooooo.

An item slightly cooler than the Old Rod can be found at the Pokémon Fan Club, located directly above the Gym. Listen to the president's boring story about his brags and he'll give you his Bike Voucher. Redeem it at the Bike Shop in Cerulean City, and you'll get a Bicycle that you can use almost anywhere to increase your movement speed.

If you come back with Surf, you can also get a hidden Max Ether five squares east and two squares north of the entrance to the Pokémon Fan Club house.

Use HM01 Cut (obtained after the events on SS. Anne) to hack down a bush and reach the Vermilion City Gym entrance. Once inside, you'll be confronted by a few trainers and a double-locked door. To reach Lt. Surge, you'll have to find the two switches hidden in the trash cans on the floor. The switches are randomly located, but once you find one, the second will be right next to it. If you don't get it on your first try, the switches will reset and move and you'll have to search again. One trick that you can do is to find the first switch, then save your game, then find the second switch, and if you get the wrong trash can, you can then reset the game which would bring you back to where you have already activated the first switch and try finding the second switch again.

You can only enter this gym once you have gotten HM01 from the S. S. Anne. If you've got it, you need to teach this skill to one of your Pokémon, then walk up to the small tree next to the gym. If one of the Pokémon in your party has Cut, it will ask you if you'd like to cut the tree.