Pokémon Horizons: The Series

Liko and the others finally locate Entei in Area Zero! However, this Entei seems kind of different from normal Entei. Liko, Roy and Dot challenge it to a battle, getting help from Friede as well, but moves that should be effective against a Fire type like Entei aren't having much effect either?! But why...? And will Liko and the others manage to overcome Entei?