Pokemon: Reborn in Unova with Memories of the Apocalypse

Pokemon + transmigration + slow development + no catching Legendary Pokemon. Pokemon descended upon Earth, and half of humanity perished. As the only person in the world who remembered Pokemon, Yan Heng spent seven years building a complete system and was revered as the Father of Pokemon. But once humanity gained power, fear followed. Cages, brainwashed Pokemon, and Hyper Beam devouring everything. When he opened his eyes again, he had been reborn in Nuvema Town in Unova, on the day he was to receive his Starter Pokémon.