Iron Boulder does not evolve and is based on Terrakion, a metal-coated, bull-like machine with axe-shaped horns. When it attacks, its horns can reshape into wide blades that look like a pointed spade. Before its official reveal, a sketch resembling it appeared in the Violet Book as a blend of the Swords of Justice Cobalion, Terrakion, and Virizion.
Excluding Cornerstone Mask Ogerpon, Iron Boulder is the only Rock type unable to learn Rock Slide. It can be considered the counterpart of Gouging Fire, as neither was revealed until The Indigo Disk released. Its English name simply means iron boulder, and its Japanese name Tetsunoiwao carries the same meaning.
Temporal Forces brought an Iron Boulder ex Double rare, Ultra Rare, and Hyper rare from 5ban Graphics plus a Special illustration rare from nagimiso, and 5ban Graphics also drew an SVP Black Star promo ex. Stellar Crown and Prismatic Evolutions each added a plain Rare, both illustrated by GIDORA.
Iron Boulder's first card, Temporal Forces' Double rare ex by 5ban Graphics
Temporal Forces' Special illustration rare by nagimiso
Prismatic Evolutions' Rare by GIDORA
No, it has no evolutionary line.
Terrakion, one of the Swords of Justice.

テツノイワオ
Rock · Psychic
Iron Boulder is a Paradox Pokémon combining Rock and Psychic typing, based on Terrakion, with no evolutions. Excluding Cornerstone Mask Ogerpon, it is the only Rock type unable to learn Rock Slide.
No published index yet — too few of Iron Boulder’s cards trade often enough to strike one.