Electric types have had their time in the sun thanks to the popularity of a certain yellow mouse. They've ended up being the face of the entire franchise; when most people think Pokémon, they think of an Electric type first. But there are a lot of other strong Electric-types out there.
So, listen, Pikachu isn't going to be on this list. We all love him. But Ash's Pikachu is an outlier. We're looking at the strongest (non-legendary) Electric Pokémon in the series.
Unlike most Electric-type Pokemon, Luxray is more of a physical attacker than a special one. Its Attack stat sits at 120, but also has a respectable 95 Sp. Atk. Unfortunately it doesn't have very good Speed or Defense, and doesn't see a lot of use in competitive battling. However, Luxray can be a useful member of a team while playing through the games. Players usually encounter its pre-evolution, Shinx, very early on and then have access to a heavy-hitting Electric/Dark-type on their journey to take down the gym leaders.
Galvantula is a speedy bugger. It's a good addition to a team when the opposing player might plan on using Grass-type Pokémon to endure Electric-type moves. Galvantula's Bug-type gives it STAB (SameType Attack Bonus) to the move Bug Buzz, which is not only super-effective against Grass, but also has a chance to lower the target's Special Defense.
Still, it isn't the beefiest Pokémon out there. Its real utility is the move Sticky Web. This slows down opposing Pokémon as long as they're not Flying-type. That makes Galvantula a great partner for for a slower heavy hitter, since Sticky Web would give it a chance to strike first.
This little anglerfish is a useful team member primarily due to its versatility. It can fill a few different niches in varied team compositions. Its greatest advantage is its high base HP of 125. Combined with the ability Volt Absorb, which makes Lanturn regain 1/4 of its health when hit by an Electric-type attack, this fish is a pretty sturdy customer. Plus it only has two weaknesses, Grass and Ground.
Lanturn also has a respectable move pool. It can be used as a support member because of its access to moves like Heal Bell. It can also deal some damage; it has a pretty good Special Attack stat and can use moves like Scald and Volt Switch to control the flow of battle.
Electivire has a very specific niche that make it extremely useful in certain situations. While it tends to be outclassed by other high-Attack Electric-types, it has a lot of moves at its disposal. It can pick up good coverage attacks like Earthquake and Flamethrower to break down enemies that might otherwise resist its attacks. It also has decent Speed, which gives it an edge over slower tanks. There are some better options, but there's no denying Electivire's a powerful ally.
The first Pokémon on the list with a mega-evolution, Manectric has incredible Speed and Special Attack. Mega Manectric takes what was already good about Manectric and makes it even better. It's one of the fastest Pokémon in the entire game. It also has the ability Intimidate, which lowers the opposing Pokémon's Attack, allowing it to survive the few attacks that can out-speed it.
Manectric isn't very bulky and can be easily taken out by certain teams, but it makes up for that with its offensive capabilities. Not only can it use its own Electric-type moves, but it also has access to some good Fire- and Ice-type coverage that can help it pick up the slack for Pokémon that resist Electric.
Poor Ampharos is a very slow Pokémon, and that means it tends not to get a lot of attention competitively, where getting a hit off first can mean everything. Most will also want to mega-evolve it before doing anything else, to take advantage of its insane 165 Sp. Atk. However, if you're willing to sacrifice a turn to get Mega Ampharos on your side, you're going to end up with a beast.
Like we said, it's Sp. Atk. stat is incredible, and it also has great Def. and Sp. Def. as well as good HP. This is a Pokémon than can take it and dish it out. Its Mega also has the unique advantage of gaining the Dragon type and the ability Mold Breaker (which nullifies opposing Pokémon's abilities), meaning it can cover an even wider number of foes than without. Ampharos might have to take a couple hits coming in, but it'll give them back just as good.
What really sets Eelektross apart from its competition is the combination of its type (pure Electric) and its ability (Levitate). These two together mean that Eelektross has essentially no type weaknesses. Levitate makes it entirely immune to Ground-type attacks. Not to mention it's a good offensive pick as well, with a wide movepool that gives it access to moves like Giga Drain and Flamethrower. It competes directly with Lanturn, which has more versatility, but Eelektross' resistances and offensive capabilities give it a step up.
Rotom-W is the form Rotom takes when possessing a washing machine. This gives it the excellent Electric/Water typing which is further improved by it's ability Levitate. The only weakness it has in this form is Grass-type moves. It doesn't have a lot of HP and very few ways to recover any hit points, but it does compensate somewhat with its high Def. and Sp. Def. It's able to go up against powerful Ground-type Pokémon with its STAB Hydro Pump and its Electric-typing make it a dangerous enemy for hard-hitting Flying types as well.
Magnezone's most useful feature is probably it's almost exclusive access to the ability Magnet Pull, which prevents opponents from switching out Steel-type Pokémon. Steel-types tend to be strong opponents with many resistances, so the ability to trap them and wear them down is invaluable. Magnezone also has very high Sp. Atk, which is excellent for its two most powerful moves, Thunderbolt and Flash Cannon. It doesn't have the HP to make it a real tank, but as a Steel-type itself, it has a lot of resistances that can keep it in the game.
A classic choice, Jolteon's the definition of a glass cannon. It's extremely fast and it hits hard with its high Sp. Atk. It doesn't have the most robust move pool, but all you really need with a Jolteon on your side is a well-placed Thunderbolt. Unfortunately, It can't take many hits, but that's what that 130 Speed stat is for.
It has some options for keeping itself out of danger. Volt Switch can pull it out of the battle while damaging a opponent at the same time. It also can have the ability Volt Absorb, which can regenerate some of its HP when hit by an Electric attack. Essentially, if you treat Jolteon right and keep it safe, it'll bring the thunder.