[OVERVIEW]
Thanks to Rock Head, Aron has access to a recoil-free 150-Base Power STAB move in Head Smash, which hits hard thanks to Aron's solid base 70 Attack. A great base 100 Defense allows Aron to survive strong physical hits, especially when coupled with an Eviolite. Its Steel / Rock typing gives it useful resistances, most notably to Fairy- and Flying-type attacks. However, its typing also gives it very common weaknesses to Water, Ground, and Fighting. Head Smash also has very low PP. It's difficult for Aron to set up on many things due to coverage moves such as Earthquake from Snubbull and Jump Kick from Doduo. Aron also has low Special Defense, meaning it can have a tough time switching in on special attacks. It faces competition from other setup sweepers that can be stronger and faster than a set-up Aron; Shell Smash users like Tirtouga and Shellder are particularly good examples. Aron also has very low Speed prior to a Rock Polish, meaning it can be KOed easily if it hasn't set up.
[SET]
name: Rock Polish
move 1: Rock Polish
move 2: Head Smash
move 3: Heavy Slam / Iron Head
move 4: Earthquake / Superpower
item: Eviolite
ability: Rock Head
nature: Jolly
evs: 196 Atk / 116 SpD / 196 Spe
[SET COMMENTS]
Moves
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Rock Polish is the main move on this set, as it doubles Aron's Speed, which gives it a chance to sweep. Head Smash is a STAB move that hits everything extremely hard and can even OHKO or 2HKO Rock-resistant threats such as Mienfoo without Eviolite after Stealth Rock. Heavy Slam hits the majority of Little Cup for consistent damage thanks to Aron's heavy weight. However, Iron Head can be used for a more reliable attack that has a chance to cause foes to flinch and also hits Pokemon that are heavier than Aron such as Onix harder. Earthquake hits Steel-types such as Magnemite and Pawniard and has perfect coverage alongside Head Smash. Superpower can be used to OHKO Pawniard and also to hit Ferroseed, which otherwise walls Aron.
Set Details
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With the given Speed EVs and a Jolly nature, Aron is fast enough to outspeed Timburr and Mareanie prior to setting up, and it is also able to outspeed Choice Scarf variants of Mienfoo and Pawniard after setting up at +2 (repetition and clarifies). Eviolite increases Aron's overall bulk, allowing it to survive Mach Punch from Timburr. The given Special Defense EVs allow Aron to take Vacuum Wave from Croagunk at full HP. Rock Head is important for allowing Aron to use Head Smash without recoil.
Usage Tips
========
Aron can switch into Pokemon that it defensively checks, such as Spritzee and Vullaby, as this allows it to immediately threaten the opposing switch-in with a strong Head Smash. Aron should be switched in on resisted hits (such as? also what scarfers do you mean?), as against Choice Scarf users, this can usually force a switch, allowing it to get a free Rock Polish. Aron can use Head Smash against slower foes when it is at low HP to deal some damage before going down.
Team Options
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Pokemon that resist Fighting-type moves, such as Spritzee and Snubbull, can help with Aron's 4x weakness to Fighting them. Grass-types such as Foongus and Pumpkaboo-XL can both handle the Water- and Ground-types that greatly threaten Aron. Those Pokemon in particular can also switch into the Fighting-types that Aron hates. Stealth Rock setters such as Onix and Dwebble can be a huge help to Aron, as Stealth Rock support helps Aron get KOs on Pokemon it wouldn't KO otherwise; for example, after Stealth Rock, Earthquake can potentially OHKO (remove double space) frail Pawniard variants like Choice Scarf. Fighting-types such as Mienfoo and Timburr can lure Fairy- and Flying-types in for Aron to set up on and can provide Knock Off support to remove Eviolites from Pokemon that would otherwise survive a Head Smash. A Steel-type spam core with Pawniard can be used effectively, as Pawniard can also use Knock Off to remove Eviolites from Pokemon that would otherwise survive a Head Smash. Diglett with Groundium Z is able to trap and remove Staryu, Foongus, and Croagunk after Knock Off has been used to remove their Eviolites. Wynaut can trap and remove Croagunk and Timburr, giving Aron more breathing room to sweep.
[STRATEGY COMMENTS]
Other Options
=============
A lead SturdyJuice set with Stealth Rock is plausible, (RC) but not recommended due to Aron's many weaknesses and it being outclassed in the role by Dwebble and Onix. If such a set is used, Metal Burst is a viable option to hit the Pokemon that threaten it for 1.5x the damage they deal. Curse is an option as a boosting move, but it forces Aron to forgo either a coverage move or Rock Polish, which it can't afford to lose due to its pitiful Speed. Heavy Slam with Heavy Metal gives Aron a strong Steel-type STAB move, thanks to Heavy Metal doubling Aron's weight, but it prevents Aron from using Head Smash without recoil. Magnet Rise mitigates Aron's crippling 4x weakness to Ground, but it also comes at the cost of replacing one of Aron's coverage moves.
Checks and Counters
===================
**Fighting-types**: Due to Aron's 4x weakness to Fighting-type attacks, defensive variants of Mienfoo and Timburr can both switch into a Head Smash and threaten Aron out with their STAB moves. Timburr, as well as Croagunk, can also threaten Aron with their priority moves.
**Physically Defensive Pokemon**: Pokemon such as Pumpkaboo-XL and Slowpoke can cripple Aron with Will-O-Wisp or directly threaten it, respectively. However, neither of these Pokemon want to switch into Head Smash.
**Water-types**: Water-types such as Staryu and Chinchou can both threaten Aron out due to its weakness to Water-type attacks and low Special Defense. Aqua Jet users such as Corphish can also threaten Aron.
**Ground-types**: Aron's 4x weakness to Ground gives it problems against Pokemon such as Drilbur and Onix, which can both take a Head Smash and threaten Aron back with Earthquake.
