• English / United States: Gladion's Type: Null / Silvally
• Japanese / Japan: グラジオのタイプ：ヌル/シルヴァディ
• Japanese (Romanized) / Japan: Gladio no Type: Null/Silvady
• Japanese (TL) / Japan: Gladio's Type: Null/Silvady

While on Akala Island, Gladion went into a cave and Gladion's Type: Null was revealed when it was released from its Premier Ball. He didn't want anyone to see it and it was restless due to the muzzle helmet on its face that couldn't be removed that time to make it a lot more comfortable. Unlike the games, it appears that Gladion's Type: Null / Silvady can change back and forth by wearing the restraining helmet and is not treated as an evolution as it initially was a Silvady then a Type: Null and then a Silvady.

Lillie became unable to touch Pokémon because she was attacked by an Ultra Beast. Gladion was so terrified he wasn't able to save her but Type: Null saved them. Gladion told Ash Ketchum the story because he trusted him but he's vowed to protect her so that she'll never experience anything that frighting ever again by becoming a Pokémon Trainer and become stronger together with his Pokémon for the purpose of defeating every single Ultra Beast there is. Because of that experience, he believes they are creatures that bring misfortune to mankind and that they should not exist in this world, including Nebby.

Silvady is a Pokémon that was created to defeat Ultra Beasts. Gladion didn't want to go into detail about its creation but he explained to Ash Ketchum that nobody must know about Silvady's existence. After Lillie was captured by Faba to wipe her memories again, Gladion's Type: Null broke through its helmet they had been trying to take off to reveal that it was a Silvady and it then turned into a Dark type. It once again fought Faba and rescued Lillie. Lillie remembered what had happened before and thanked Silvady for rescuing her and gave it a hug, touching it and finally getting over her fear of touching Pokémon now that her memory was restored.

In Alola Pokémon League semifinals first match, Kiawe's Turtonator battled against Gladion's Type: Null / Silvally as the last matchup as Turtonator defeated Gladion's Lycanroc (Midnight Form) leaving Kiawe and Gladion have one Pokémon remaining. Turtonator learned the move Focus Blast during the match and it was super effective against Gladion's Lycanroc. Turtonator used Shell Smash in its battle with Silvally which allowed it to increase both its speed and attack power. To withstand the Inferno Overdrive Z-Move, Gladion changed Silvally into a Fire type and that was the turning point in the match. With Turtonator tired from its battle with Lycanroc and using an all out Z-Move, Silvally outlasted it and finished the match with a Crush Claw to defeat Turtonator and advance Gladion to the finals.

In the first match-up of the Alola League finals, Ash's Melmetal faced off against Gladion's Type: Null / Silvally. Everyone was surprised when Melmetal was revealed and it burst onto the scene with Double Iron Bash. It hit with a lot of power but Gladion adapted by moving around a lot. Melmetal took on massive amounts of power as soon as it evolved but Silvally’s fancy footwork proved to be hard for Melmetal to actually hit it. Half way through the battle, Silvally has changed into a Fighting-type Pokémon and attacked with Multi-Attack but Melmetal showed just how tough it is by standing its ground. Melmetal was defeated by Silvally and Pikachu came out to replace it. Pikachu's unconventional use of Electroweb to bounce off it like a boxing rings ropes allowed it to finish off Gladion's Type: Null / Silvally with an Iron Tail.