The Aura Trio (also known as the Yggdrasil Trio and the Axis Trio by some) is a trio of Legendary Pokémon that originate in the Kalos region and comprises Zygarde, Xerneas and Yveltal. The three members are based on Yggdrasil, which is a huge tree in Norse cosmology. It is said to be protected by three guardians. A bird protects the upper part of the tree. A deer protects the soil of the tree. A snake protects the underground of the tree. The same is true for Xerneas, Yveltal and Zygarde.
|Fairy||Fairy Aura||Xerneas is the Fairy-type member of the trio. It is said to be the giver of life. It protects the soil of trees. It has a calm nature and the ability to stop destruction. Its signature move is Geomancy.|
|Dark/||Dark Aura||Yveltal is the Dark/Flying-type member of the trio. Yveltal is the angry Pokémon and the sign of destruction. It protects the upper part of the tree. Its signature move is Oblivion Wing.|
|Dragon/Ground||Aura Break||Zygarde is the Dragon/Ground-type leader of the trio. Zygarde protects the environment and the underground of the tree. Its signature moves are Land's Wrath, Thousand Arrows, Thousand Waves and Core Enforcer.|
- Yveltal, unlike Xerneas and Zygarde, does not have a second form. Xerneas has Neutral and Active Mode, while Zygarde has the Cell, Core, 10% and 100%, alongside its 50% Forme.
- Xerneas and Yveltal both have types that are immune to Zygarde's. Xerneas, being a Fairy type, is immune to Zygarde's Dragon, and Yveltal, being part type, is immune to Zygarde's Ground type.
- They all resemble the letters their names start with, Yveltal resembling Y, Xerneas resembling X and Zygarde resembling a Z.