“It's said that Hydreigon grew ferocious because people in times long past loathed it, considering it to be evil incarnate and attacking it relentlessly.”
In Pokémon Mystery Dungeon: Gates to Infinity, Hydreigon was at first described by Munna as an evil Pokémon who is pure destruction in Pokémon form, devours everything in his path, and said to be the cause of the world's balance being disrupted. In truth, Munna's words about him were all a lie to trick the player, and Hydreigon is really the physical embodiment of the Voice of Life, the form of the world's will to live, who called upon humans to save the Pokémon world as no Pokémon could hope to save it. He originally first contacted the player through a dream before Munna intercepted the vision, and by using Hydreigon's voice, she tricked the player into thinking Hydreigon was evil.
It's said that Hydreigon grew ferocious because people in times long past loathed it, considering it to be evil incarnate and attacking it relentlessly.