Gladion's Silvally (Legend Heroes)

Gladion's Silvally is a Legendary Pokémon he obtained in Alola.

Prior to Legend Heroes: Sun & Moon
Silvally was a Pokémon created to fight Ultra Beasts. Four years ago, Silvally was created by an evil scientist of the Aether Foundation, Faba. During his research, Faba attempted to release an Ultra Beast into the Pokémon world in hopes of fulfilling Lusamine's dreams. However, a Nihilego emerged from the Ultra Wormhole and attacked Lillie. Faba and Gladion couldn't do anything but watch in horror until Silvally came and saved Lillie's life. Afterwards, Faba declared Silvally as a failure and placed restraints on it, which caused it to de-evolve into Type: Null. Its daring rescue as well as its appearance unintentionally caused Lillie to become fearful of touching Pokémon.

In Family Determination!, Gladion used Silvally to help him and his sister overcome obstacles on the way to the Altar of the Sunne. Standing right before the altar was a horde of Jangmo-o and Hakamo-o, led by a Totem Kommo-o. Thanks to the help of Lillie and Snowy, Gladion was given enough time to give Silvally a Fairy Memory, allowing to resist Kommo-o's attacks and defeat it. Silvally was later used to battle Lusamine's Absol alongside Gladion's other Pokémon. Having its feet frozen in place by Absol's Ice Beam, Gladion used a Fire Memory, allowing Silvally to melt the ice and counterattack. This released the hold it had on Gladion's other Pokémon thanks to its Mean Look. Gladion later used a Steel Memory to change Silvally to a Steel-type, allowing it to ferry him across the sea of poison the Nihilego-possessed Lusamine left behind.

Silvally and Gladion reappeared in SM087, where Gladion had to calm it down again. Gladion recognized its behavior as a bad omen. It was later sent out as its Trainer and the other Ultra Guardians witnessed an Ultra Wormhole form in front of the moon, where it sensed two presences coming out. In the next episode, Silvally teamed up with Pikachu to free Nebby and Lunala from Team Rocket's electric net. In SM089, it was revealed that Silvally was able to perform Breakneck Blitz, which it used along with Ash's Pikachu, Kiawe's Marowak, and Lana's Popplio's Z-Moves to help separate Nebby from Necrozma and to give Necrozma enough Z-Power to turn it back into its true form. However, this attempt failed as the amount of Z-Power was too little and Necrozma used it to power itself up instead. Silvally later joined the rest of Alola in showering Necrozma with Z-Power, causing it to separate from Nebby and revert to its normal form. Necrozma still had not absorbed enough Z-Power though and tried to capture Nebby again, but was stopped in its tracks by Silvally who attacked it with Air Slash.

Personality
Silvally has the ability to sense the presence of Ultra Beasts and Ultra Wormholes. Silvally often becomes stressed when it senses danger, barking and lashing out when it feels threatened. As a Type: Null, its helmet was also a source of anxiety for it. Despite its anxiousness, it appears to trust its Trainer, and can be calmed down with Gladion's words. It eventually became able to trust Gladion enough to use the full extent of its power, breaking its restraints. It also has a strong connection to Lillie, having saved her from Nihilego during her childhood. It inadvertently caused Lillie's fear of Pokémon, and was ultimately what caused her to stop fearing them. For whatever reason, Gladion wants Silvally's existence to remain a secret.

After breaking its mask, it gained access to the RKS System.

Trivia

 * Prior to its evolution, Type: Null was the first Pokémon to be nicknamed as its evolved form, Silvally.
 * Unlike most other Pokémon in the anime, Silvally is not kept inside of a normal Poké Ball, instead being housed in an Premier Ball.
 * Silvally is the only Pokémon capable of using Breakneck Blitz in the anime to not be owned by Ash.