Research Notes - Onix
Petra vermis

Onix are rock-based Pokémon, putting them in the same family as Golem and Probopass. Their evolution Steelix, however, have metallic bodies, leading many to question why they are not classified alongside the likes of Klinklang and Metagross. Research shows that the extreme density of Steelix results from the extreme pressure of their underground habitats alongside their lithophagous diets. Trained Onix will not evolve into Steelix without the use of the synthetic Metal Coat. Thus, although Onix are capable of evolving into the metallic Steelix, they are naturally born with rock-based bodies and are classified as such.

---

Diet

Both Onix and Steelix are lithophagous, eating rocks as they burrow beneath the earth’s surface. Onix that consume lots of metal ore are more likely to evolve into Steelix; Steelix actively seek out iron ore in particular to strengthen their own bodies. ​

Care

These Pokémon are rather clumsy aboveground, as their bodies are adapted to tunneling through solid earth. They will leave large holes in the ground as they burrow, which can be freely used by other subterranean Pokémon. These Pokémon should be kept away from magnets, which can disrupt the magnetic organs in their heads. Onix are particularly weak to water and stay away from the substance at all costs.

Caution

Neither of these Pokémon are particularly aggressive, though Steelix are slightly more confrontational than their pre-evolutions. These Pokémon are commonly encountered in subterranean environments, where their large statures can sometimes unintentionally make them hazards, especially in tight tunnels. Their tunneling is also known to cause earthquakes and weaken foundations when too many intersecting tunnels are burrowed underneath structures.

---

Behavior

Onix are distrustful Pokémon. They dislike humans in their territory and will try to stay away if possible. They tend to fight when they sense danger. (-1 / 1 / -1)

Steelix are territorial Pokémon. They dislike humans in their territory and will act aggressively towards them. They almost always fight when they sense danger. (2 / 1 / 2)