Hiroki is a Pokémon Trainer that battled against Ash's Rockruff
and Ash Ketchum
at the Pokémon School. He lost the battle after Ash's Rockruff
used the Z-Move Ultra Dash Attack.
Hiroki is based off of Hiroki Kobari (古張裕起) who's stage name is Abareru-kun
, one of the hosts of Pokénchi
. He revealed on Pokénchi #75
that this character Hiroki was based off of him.