Hariyama debuted in To Top a Totem!, where it assisted Hala in clearing some logs from the road. These logs were revealed to have been dropped by a group of trouble-making AlolanRattata and Raticate.
In Trial and Tribulation!, Hariyama was Hala's final Pokémon in his grand trial against Ash. Hariyama went up against Pikachu, but was soon defeated by Breakneck Blitz, giving Ash the win.
In Securing the Future!, Hariyama joined the rest of Alola in showering Necrozma with light so it could return to its true form. Afterwards, it and Hala used their Z-Move to shower Necrozma in a blinding amount of light.
Hariyama is a strong Pokémon, as seen in Trial and Tribulation!, where it proved itself to be a tough opponent for Ash's Pikachu. Outside of battle, Hariyama is rather gentle, as seen in To Top a Totem!, where it allowed Rotom to photograph it and also allowed Pikachu to climb over its body.