Once, there were no humans on the island. The Nosepass lived unmoving, as they had since birth, in a long line through the cave at the island's center; they fed by attracting scrap from dead steel-types with their magnetic noses.
Then the humans came. They mined the cave for resources, but somehow determined they were gods. They carried the Nosepass out to the north side, facing the sea. Every clan, tribe, or city would try to outdo each other, building them higher and higher platforms and sacrificing to them more and more steel. And still they did not move.
Then the island was mined dry. The drive to please the Nosepass had gone too far, and stone and steel alike were gone. Without these resources, civilization collapsed. The people turned their anger on the clergy, and when they learned they could defy them without bringing anyone's wrath, they grew bold enough that they tore down their platforms and toppled their gods. The people fought each other for food and died off until only a hundredth of their number remained. The Nosepass lay facedown for a hundred years. And still they did not move.
Then the island was found by explorers on Lapras who had come from the outside world. The pokeball spread to the island, and a brave few concluded that the face-down creatures were not false gods left behind to remember their ancestors' folly, but pokemon like any other. They captured them. They brought them back to the cave they had called home when their ancestors first discovered the Nosepass – not for ritual, but to see what they could do against the pokemon of the cave. And they fought, but did not move.
Then they gained so much experience that their form changed. And then the Probopass moved.