The circle of mountains near Kyurem's were almost like the Ultra beast ruins back in Alola. The pillars from there seemed to be replaced by the mountains themselves, and the ground was covered with sand instead of stone.
To their luck, Xerneas was right. Necrozma was perched on top of a rock spire near the back of the mountains. Once all three of them were close enough, Necrozma slowly turned around to face them.
"I was expecting you to eventually come here…" Necrozma said to them. "You all came sooner than I expected, just on time to see the mountain fall. However…" Necrozma stared at Giratina, who winced at Necrozma's gaze. "There is still time to understand, Giratina." He said to him. "I'm only doing what is best for me and my dimension. Your sacrifice is for the greater good. So please, let me restore myself so I can restore my home."
Giratina went quiet, trying to find a response good enough for Necrozma.
"Listen, I do understand, but I can't let you take our world's light." He said to him finally. "There are thousands of Pokémon here who want nothing more than to live, and I can't let you take it away from them just so you can live. If you do this, you'll only cause more destruction than before." Giratina glared at him, his voice hardening. "Like I said, my role is to protect this world. I'll do anything to make sure that you won't get away with this."
Necrozma stared at him. Even though Necrozma had no eyes, Giratina could see the anger flowing through him.
The clearing was silent, before Necrozma let out a laugh.
"It's a shame, Giratina…" Necrozma said to him, taking a few steps forward. "Truly a shame that you refuse to listen to me!" And with that, the sand on the ground turned black. Seeming to take the form of shadows now, with shadows of various Pokémon with white eyes forming and rising out from the ground, growling.
Giratina tried not to waste any time and ran towards Necrozma, preparing Ancient Power at him when one of the Pokémon in the form of a Lycanroc dove at him, biting down on his neck. He let out a cry and tried to throw him off, but there seemed to be hundreds of Pokémon shadows coming in and tackling him, Xerneas, and Regigigas.
Necrozma finally dove down and shot Power Gem at him and threw him across the clearing. By the time he was up, he saw Xerneas throwing the Pokémon shadows off of her and firing Aurora Beam at Necrozma. Regigigas came in after to hit Giga Impact at him, but Necrozma was already getting up to his feet and preparing Prismatic Laser right at him. Regigigas and Necrozma's moves clashed, resulting in bright light that engulfed the entire clearing within the mountains. Giratina staggered back due to how bright it was. He saw that some of the Pokémon shadows that were filling up the clearing had disappeared completely, some of them were still standing, but other than that, the clearing was not as filled with them as before.
Giratina took his chance and ran towards Necrozma, avoiding the Pokémon shadows that were coming out from the black sand and fired Ancient Power at Necrozma again. He had used Iron Defence to block Giratina's attack, but Giratina quickly followed the Ancient Power with Shadow Claw, sending Necrozma down to the ground.
Necrozma got up by the time Xerneas was coming in to land Night Slash. He got out of the way in time, and attempted to use Prismatic Laser again right at her. Giratina used Shadow Force before he could, however. He soon found himself tackling Necrozma to the ground, but was thrown off of him almost immediately after and was about to get hit by Power Gem before Necrozma was hit by Night Slash from Xerneas.
Regigigas came in, in an attempt to keep Necrozma down with Ice Punch before he got up again. Although, was already on his feet, raising his hands so that more Pokémon shadows would rise up from the ground and tackle Regigigas. Even though they were everywhere, Regigigas threw them off and kept going before he finally stuck his Ice Punch the moment Necrozma used Psycho Cut on him. They traded blows for a moment, before Regigigas missed one of his Ice Punches, giving Necrozma a chance to land one of his Psycho Cuts on Regigigas's back. Giratina was already running to Necrozma at that point however, and with one more Shadow Force, Giratina sent him across the clearing.