>>45136983Not that guy, but personally? Have the first stage be one long stone, then have that evolve into a group of them that form a sort of colony. They assemble into stonehenge-like formations, shuffling and shifting, connecting with one another at their axises through some unknown force. Stonejourner's small block arms are replaced with additional long stones, and the legs are shortened-- all the pieces would roughly be uniform. Attacks are more like one rock swinging from the main body, then snapping back. They'd move like a Jakob's Ladder toy. Focus on how people don't understand how they stay in place, connect, transfer information, why they join up, or where they even come from. If it's not Rock/Psychic, give it a shit ton of Psychic attacks. Maybe there's a middle stage which just two stones, too, but it's not strictly necessary.
This concept has already been touched on by Stakataka, unfortunately, which is a series of small living bricks making up a cube. It's not identical, quite, in that Stakataka are a hivemind, but for this henge mon, there's one clear boss stone that seems to be controlling the others. The only consolation, then, is the prominent theory that these are Galarian Stakataka-- Stakataka that became stranded in Galar and adjusted to life outside the Ultra Space.