Lycanroc is one of Gladion's partner Pokémon and is often seen with him outside of battle. Despite how it looks, it's a caring Pokémon, friendly to Ash's Rockruff to the point of helping convince Tapu Lele to heal Rockruff before it evolved. It is a very strong Pokémon, often the Pokémon of choice in Gladion's battles as it has access to powerful moves including Stone Edge, Crunch and Counter. With Gladion's Rockium Z, Lycanroc can use Continental Crush and with the Dragonium Z it can use Devastating Drake

Umbreon is another of Gladion's Pokémon. First encountered as an injured wild Eevee that he found and took to Hobbs, it eventually evolved into Umbreon. It is often seen out of its Poké Ball with Gladion but despite that, it hasn't been used in battle much. It knows the move Dark Pulse and Shadow Ball

Silvally evolved from Type: Null during an incident in the Aether Paradise where Lillie was under attack from Faba. It gained the ability to use Memory Disks and has the move Multi Attack at its disposal that it used to stop Faba from taking Lillie, saving Lillie again. It has many strong attacks and can even use the Z-Move Breakneck Blitz

Zoroark was Gladion's father's partner Pokémon and was used by Mohn as he participated in the Grand Trials of Alola. While Gladion was looking for his father on Melemele Island, he searched for the Zoroark, which was following him disguised as other Pokémon. After finding Zoroark, he informed Zoroark that he believes his father is alive and requests Zoroark's help to find him. Zoroark agreed and joined with Gladion.

When Gladion, Lillie and Lusamine went to The Crown Tundra, they found Mohn alongside a shiny Nihilego, which Mohn called Lillie. It had found Mohn after Mohn fell through an Ultra Wormhole, it took him back to his own world and stayed with him. Gladion eventually caught it so it can stay with the family.

Type: Null is a Pokémon in Gladion's care. It once saved Lillie from a Nihilego and Gladion decided to take care of it. Due to its nature, it is never out of its Poké Ball outside, often being seen in a cave with Gladion. It is often under great discomfort due to its helmet but Gladion manages to keep it calm. It had strong moves like Swords Dance and Crush Claw at its disposal. It then evolved into Silvally to help Gladion protect Lillie