Ultra Burst (Japanese: ウルトラバーストUltra Burst) is a transformation affecting Pokémon that was introduced in Pokémon Ultra Sun and Ultra Moon. Pokémon that have undergone Ultra Burst are distinguished by the word "Ultra" in front of their species name. So far, the only known Pokémon to have this transformation is Necrozma. Ultra Burst is similar to Mega Evolution and Primal Reversion, but instead of using the energy of people and Pokémon or the power of nature, Ultra Burst uses the light of another Pokémon.
Ultra Burst may only be activated once per battle; any other Necrozma in the user's party will not be able to become Ultra Necrozma even if it is also holding an Ultranecrozium Z. Necrozma will revert to its original form if it faints in battle and cannot activate Ultra Burst even if it is revived.