Electric-types in the main Pokemon games hold a unique niche in the type chart. They are usually geared towards offense with their Speed being one of their best stats. This, in combination with paralyzing moves like Thunder Wave, can make them some of the best leads in almost any battle. Attacks of this type can often unleash devastation onto an opponent's team in the blink of an eye with some powerhouse moves to choose from. Despite its less than stellar accuracy, Thunder is one of the most renowned for zapping adversaries into submission.
Since Electric attacks are super effective against some of the most common types, like Water and Flying, Thunder also makes for a great coverage move on even those Pokemon who do not get a Same Type Attack Bonus (STAB) from it. Although it should be mentioned that there are also some Pokemon that can learn this move and have no practical way of making use of it. There are quite a few unexpected Pokemon who can learn this tremendous triumph for the Electric element.
Disclaimer: As long as a Pokemon can learn Thunder in one generation of the games, it will be considered.
10 Raticate
Even though Raticate and The Pokemon Company's mascot Pikachu are both classified as "mouse" Pokemon, their similarities are quite scant. They share a similar body plan and are both in the Field egg group, however, that's about it in terms of physical relation. Though, it should be mentioned that this egg group is full of diverse pocket monsters.
Yet, this Normal-type rodent can also learn the terrifying Thunder move via Technical Machine (TM). Although, with a terrible Special Attack stat it is very much a waste of a move slot on Raticate. In every situation, except against a Ghost-type, this rodent Pokemon's Super Fang will always be significantly more effective in injuring the foe.
9 Primeape
There are few Pokemon that can match the rage and intensity of a battle-ready Primeape. This Fighting-type excels at using strategies that take advantage of any of its anger-based abilities. Vital Spirit prevents it from being affected by sleep-inducing status moves and Anger Point grants it a ridiculously huge boost to its Attack if struck by a critical hit.
Also being in the Field egg group, this pig-monkey Pokemon gets access to many more moves than one expects. This grouping for Pokemon breeding is full of ground-dwelling species and they are known for movesets as versatile and varied as the land itself. Because of this, Primeape can learn Thunder from a TM as well. Though, with stats aimed more at physical offense, non-contact moves like these don't do very much damage.
8 Gengar
This shadowy Ghost and Poison-type does not really have any qualities that make it an obvious user of Electric moves, though it is a Pokemon that can make great use of them. Gengar can learn Thunder by Technical Machine and has a Special Attack stat that allows it to use this shocking summoning of lighting very well.
With a base Special Attack stat of 130, Gengar can annihilate foes of many types with its mostly neutral-hitting Ghost attacks. However, one threat that these Ghost-type attacks can't do anything against is Normal Pokemon due to their type-immunity. The most dangerous of these are the faster ones, which usually end up being part Flying-type. Gengar can use this mightly Electric attack to zap any such foe before they can cause too many problems.
7 Reuniclus
As s blob with loosely-formed arms that represent cell division in real-world biology, there isn't a tangible reason that Reuniclus should be able to learn Electric attacks, let alone one of the strongest of them. However, this is another species that can learn Thunder with a TM.
This Psychic-type may not fill the same niche as an Electric-type Pokemon using this bold bolt, however, it has a significant Special Attack stat of 125 that can capitalize on the big damage that Thunder can inflict. Reuniclus' incredibly low speed will mean that they will likely take some damage before unleashing the lightning, though, this can be alleviated by setting up Trick Room to allow slower Pokemon to move first.
6 Dragalge
Unique type combinations like what is seen in Dragalge, the dual-type Poison and Dragon Pokemon, are always novel to players looking for a new favorite to try out in battle. Being in the Dragon egg group allows this Pokemon to learn many elemental moves that it normally would not be able to.
Dragons are mythical creatures that are said to be more in touch with the energy of the world than many other types, granting them a decent lore-friendly reason to learn moves either by leveling up or TMs like Fire Blast, Ice Beam, as well as the devastating Thunder. Dragalge's Special Attack stat of 97 gives is some nice potential with powerhouse elemental moves.
5 Blissey
Although everyone's favorite Special Defense wall is much more of a healer than a fighter, Blissey comes with some great special attacks, Thunder being one of them. When taught this move with a TM, this pink pocket monster of happiness can zap foes with impunity if there is no physically-oriented Pokemon to challenge them.
One of their potential abilities, Serene Grace, doubles the chance of secondary effects of moves activating, meaning that Thunder's normal 30% chance to paralyze is increased to a whopping 60%. In addition to greatly reducing the HP of many adversaries, Blissey can also cripple foes quite easily.
4 Starmie
Since Starmie, the Water and Psychic-type, is weak to Electric attacks, it seems very odd that they would be able to produce and use such an element without severely injuring themselves. However, Starmie defies logic by being able to learn Thunder thanks to a TM.
Interestingly, they are also one of the best suited for this move. Firstly, they have an excellent Speed stat of 115, allowing it to both literally and figuratively shock foes because they can react. Next, its Special Attack of 100 grants it the power to truly hurt foes with its special moves. Lastly, this lets them hard-counter the many other Water-types in the game.
3 Rhydon
Here's a Pokemon that makes absolutely no sense to equip with Thunder. Although Rhydon deserves respect for being the first Pokemon to ever be conceived and designed, it is a Ground and Rock-type specifically intended to do the opposite of what Electric-types are known for.
Rhydon boasts high physical Attack and Defense, along with high HP, which makes it very usable in battle. However, this is only the case with a moveset that takes advantage of its strengths. Giving it Thunder via TM to use with its pathetic 45 base Special Attack is a surefire way to squander this mighty monster's potential.
2 Mimikyu
Despite looking like everyone's favorite Electric mouse from afar, up close it is quite clear that this is an imposter Pikachu. Mimikyu, the Ghost and Fairy-type, actually has no relation besides wearing a disguise that mimics their appearance. They aren't even in the same egg group, with Pikachu being in the Field and Fairy group while Mimikyu only being in the Amorphous one.
This does not stop Mimikyu from learning Thunder by TM, for its desire to imitate the franchise mascot seems to be powerful enough to surpass strategic relevance. Mimikyu can't even make great use of this Electric move with its very low base Special Attack stat of 50.
1 Castform
Those Pokemon that usually rely on gimmicks tend to be lackluster in actual competitive play, though Castform can be an exception to this notion if their trainer plans accordingly. Being able to shift forms depending on an active terrain effect grants this Normal-type different elemental forms that can make the best use of the weather conditions used to change their shape.
Thunder, learned by TM, can be one of the best choices for trainers intent on using Castform's Rainy Form the most. Since this weather Pokemon learns Rain Dance by leveling up, it would be easy to slap Thunder into a move slot to take advantage of the 100% accuracy that this downpour gives this storm-borne strike, negating the only real downside to the move.