An Arbok's scales come in six different patterns, and a skilled one can switch between some of them at will. The standard pattern is regeneration, and the three most commonly shifted to are invulnerability, attack, and speed. Status Arbok are rarer, and probably among the stronger forms: their gaze is said to petrify, and their poison, no mere annoyance, debilitates so quickly as to often make the difference in battle.
The sixth pattern is far and away the most powerful, but so mysterious and difficult to perform that even Agatha of the Elite Four could not train her Arbok to use it. It is rumored that Giovanni of Team Rocket keeps one in his collection, but this rumor holds little veracity: if he possessed such a strong pokemon, he surely would have used it.
The historical record shows many depictions of this Arbok, performing amazing feats such as slaying Dragonite and battling whole villages. None of these depictions included the actual pattern, for it is said that the Arbok either moved too fast to draw it or killed anyone who tried. Legends ascribe other powers to it, such as being able to burrow through solid rock and being worshiped as a god by other snake pokemon, although the veracity of these tales is often in doubt. Despite having never been caught or even properly recorded, the ultimate pattern Arbok's existence is widely acknowledged by scientists, most of whom hold out hope that one can someday day be captured for further study.