"Very well then." Tucking the light orb under his right arm, Necrozma leaned back against the sandy mound and crossed his arms. "You know Cabot? Well, on my planet, his kind does not exist." His core dimmed. "In the earliest years, pokémon were struggling to come to grips with their existence. They were driven only by primal survival urges. Yet, as the years went by, they learned from their environment... and from one another. Slowly, they began to adapt. To work cooperatively. To live communally... as the pokémon in Treasure Town do.
"But there were some species that did not accept such changes." Necrozma stared into his right hand. "They continued to let their savage instincts guide them. They would attack the communities and harm the pokémon seeking peaceful lives." He leaned over and scooped sand up into his hand. "I would not stand for such injustice. So, with my powers, I rounded up each and every one of these disrespectful species. Then, in a storm of meteors that history has come to call the 'Great Cleansing'..."
Necrozma closed his fist. Pink and black energy crackled around his hand. He opened it up and the now-blackened sand grains were carried off into the ocean by the breeze.
"... I wiped them out of existence."
He tapped his right hand against his temple. "It is such a shame the cranidos and rampardos of my planet could not have been more like Cabot. Perhaps they would still walk Etherium if they were."