Aron

The Bulgasari of Korean legend is a monster that eats iron and grows fatter with every bite. That is where the idea comes from, crossed with an armoured dinosaur from the nodosaurid family and the riveted plates of an ancient suit of armour. The Pokédex entries make no attempt to hide it: it lives in high, inaccessible mountain areas, and when hunger takes hold it comes down to bite rails, bridges and vehicles. One of them describes it demolishing a rubbish truck with a full-force charge, then eating it.

That diet serves a specific purpose. The armour covering its body is made from the iron ore it extracts from rock, and when it evolves it does not keep it: the whole shell falls off, and a new one forms underneath. The latest entry adds that these discarded shells used to be collected and put to use.

It is 40 centimetres tall and weighs 60 kilograms, so most of what is there is metal. Its official category, the Iron Armor Pokémon, sums it up better than any description of the animal underneath. It is the first of a three-stage line that reaches Aggron via Lairon, and the only one of the three that can still fit in one arm.

Its 330 base stat total is badly distributed even for a first-stage Pokémon. The 100 Defence is the good number; 70 Attack is usable; 50 HP, 40 Special Attack, 40 Special Defence and 30 Speed are dead weight. It yields 1 Defence EV when defeated, exactly as its data suggests.

Sturdy, its usual Ability, guarantees survival at 1 HP from any hit received while at full health. Combined with Endeavour — an Egg Move — it creates the only trick that makes Aron dangerous: it survives the first attack, brings the opponent's HP down to match its own and leaves the exchange one hit away from either side. Rock Head is the other option, and it is not merely decorative: it removes the recoil from Double-Edge, learned at level 56, and Head Smash, another Egg Move with 150 power. Heavy Metal, its Hidden Ability, doubles its weight to 120 kilograms and increases the power of Heavy Slam, learned at level 52.

Offensively, Steel and Rock get in each other's way less than they might, but they still do not cover much: Iron Head at level 28 and Rock Slide at level 24 are the serious attacks of the first thirty levels. Defensively, the combination resists ten types and nullifies Poison, while reducing Normal and Flying damage to a quarter. The problem is the multipliers going up. Fighting and Ground hit for four times damage, and Water for twice. With 50 HP, an Earthquake from either side ends the conversation before Sturdy can matter twice.

In a normal playthrough, its role is an early physical wall against Normal- and Flying-type opponents. With 30 Speed, it always moves last.

It belongs to a single Egg Group, Monster, which lets it breed with the heavy dinosaur and reptile lines in the Pokédex. The gender split is even, with 50% female, so breeding your own line does not depend on the luck that other species demand.

Its 35 Egg Cycles work out at roughly 9180 steps, among the longest stretches there are: twice as long as an ordinary starter takes. Combined with a Slow growth rate, getting a useful Aron costs time in both senses.

Of its eleven Egg Moves, the ones that change anything are Endeavour, because of what it does with Sturdy; Head Smash and Superpower, both with 120 or more power; Curse, which raises Attack and Defence in exchange for Speed it does not have; and Reversal, which hits harder the less HP it has left. Iron Head also appears through breeding in addition to being learned at level 28.

It evolves into Lairon at level 32, and that evolves into Aggron at level 42. No stones, no items, no time restrictions. Its habitat is the mountains, and some wild specimens carry a Hard Stone. Its catch rate is 180, a comfortable number: a normal Poké Ball is almost always enough.