While Magneton may appear to be outclassed by its evolution, Magnezone, Magneton's higher Speed stat gives it a specific niche. With a Choice Scarf or a Salac Berry boost, Magneton has the ability to outspeed a much bigger portion of Pokemon in the OU tier than Magnezone, allowing it to both revenge kill more threats and avoid being revenge killed while it's sweeping. Magneton still has the rare ability to trap and remove Steel-types from the game with Magnet Pull. When using Magneton, always remember to abuse its higher Speed, or you are better off using Magnezone.
With a Choice Scarf attached, Magneton reaches 393 Speed, enough to outspeed many dangerous threats such as Adamant Dragonite and Gyarados after a Dragon Dance, Jolly Tyranitar after a Dragon Dance, and Starmie. Magneton can then proceed to revenge kill all of them with the appropriate move. Thunderbolt OHKOes Gyarados and Starmie, Hidden Power Ice destroys Dragonite, and Flash Cannon can pick off weakened Tyranitar and OHKOes Weavile. Explosion is always a good move to allow Magneton to go out with a bang, potentially taking down an opposing Pokemon in the process. Hidden Power Fire can be used if you want to quickly kill Scizor and Forretress. Note that Magneton will Speed-tie with max Speed Adamant Gyarados if you choose to use Hidden Power Fire.Team Options & Additional Comments >>>
This set takes advantage of Magneton's decent Speed and many resistances (Steel in particular) to set up a sweep. The idea is simple: switch in on a resisted attack from an opposing Steel-type, preferably Choiced (for example, Choice Band Scizor's Bullet Punch), set up a Substitute, and use Charge Beam to raise Magneton's Special Attack. Once the Substitute is broken, Magneton can continue to use Substitute until it reaches 25% HP or less, where its Salac Berry will activate, shooting its Speed stat to 393. Magneton can then proceed to sweep weakened teams with its boosted Speed and Special Attack. Like Agility SubPetaya Empoleon, Magneton has resistances to common priority attacks used in the standard tier while having immunities to Toxic Spikes and sandstorm, as well as a resistance to Stealth Rock.
Substitute, in conjunction with Salac Berry, and Charge Beam are the core of this set, allowing Magneton to increase both its Speed and Special Attack stats, respectively. In the last two slots, there are quite a few options to use. The preferred combination to use is Charge Beam + Flash Cannon + Hidden Power Grass, which gives maximal coverage while being able to OHKO Swampert (which would otherwise wall Magneton). If you prefer to have a stronger Electric STAB, Thunderbolt and Hidden Power Ice can be used for maximum coverage between two moves. Finally, Thunderbolt and Flash Cannon can be used if you have Pokemon that can reliably weaken or remove Ground-types.Team Options & Additional Comments >>>
While Magneton has the same movepool as Magnezone, its lack of bulk makes a lot of other options harder to perform, so they are generally better left to Magnezone. Such options include the traditional Substitute SteelKiller set, Choice Specs, and Dual Screens. Magneton also has other moves at its disposal, such as Discharge and Thunder Wave, but again, these moves are better used by Magnezone, which boasts more impressive bulk.
On the Choice Scarf set, one can sacrifice some Special Attack EVs to power up Explosion a little more. However, if one were to add some Attack EVs onto Magneton, make sure that its Special Attack stat does not fall any lower than 327 (which is no less than 204 Special Attack EVs). This is because Magneton will lose the guaranteed 2HKO on Jolly Tyranitar after Stealth Rock damage.
Checks and Counters
Magneton's counters are essentially the same as Magnezone's. Blissey and Snorlax's massive Special Defense lets them take any attack that Magneton can throw at them with ease (barring Explosion). Celebi can also absorb most attacks that Magneton uses, but must watch out for the occasional Signal Beam, which will OHKO it. Lastly, Rotom-A can also switch into Magnezone without much trouble, but must rely on Overheat or Hydro Pump to do significant damage to it.
Depending on which Hidden Power Magneton runs, Flygon, Gliscor, and Swampert can counter Magneton. Zapdos can OHKO any Magneton with Heat Wave, but will detest taking Thunderbolt or Hidden Power Ice. While Choice Scarf Heatran will not enjoy switching into Thunderbolt or the rare Hidden Power Ground, it can outspeed all forms of Magneton and OHKO with a Fire-type move or Earth Power.
Dugtrio can trap and OHKO Choice Scarf Magneton that are locked into Thunderbolt. Opposing Magneton and Magnezone can also trap and KO Magneton that are not using Hidden Power Fire or Hidden Power Ground. Electivire can switch into Electric-type attacks, obtain a Motor Drive boost, and proceed to OHKO Magneton with Flamethrower, Cross Chop, or Earthquake. Thanks to Volt Absorb, Lanturn and Jolteon can switch into Electric-type attacks with impunity while resisting most of the other attacks that Magneton can throw at them.