Kiawe sent Marowak to battle Sun, to test if he was worthy for the Island Challenge. Sun sent Dollar, who started blocking Marowak's attacks. Marowak, however, used Flame Wheel to hurt Dollar, while Moon noted Marowak had a blue flame and suspected it was a regional variant. Marowak continued attacking, as Moon's Rotom explained it was a Ghost and Fire-type Pokémon. After Dollar was hit by Marowak's Shadow Bone, Sun was forced to have his Dollar keep an eye on Marowak's attacks, and let it hit Marowak. Dollar did so and hit Marowak with Feint Attack. Before Kiawe could continue, he was called by his boss, who threatened to fire him from his job. Kiawe persuaded them to keep his job and approved that Sun could take on the Island Challenge.
Kiawe and Marowak fought Gladion and the Team Skull grunts. The two were defeated at the Memorial Hill, where Sun, Moon, Lana and Mallow found them. Marowak followed Kiawe to the Ruins of Life, where Kiawe taught Sun how to use Z-Moves. After the battle with Gladion, Tapu Lele healed everyone with its power, and used Psychic Terrain to initiate a battle. Kiawe had Marowak attack Tapu Lele with the rest of the group's Pokémon, but was easily blown away by Tapu Lele's power.
Kiawe's Marowak participated in the battle against the mysterious creatures, named Ultra Beasts, that Guzma sent to attack at Po Town. It fought an alluring Ultra Beast, but was wounded in the battle.
Kiawe and Marowak spent time on Exeggutor Island for training, and battled against Mallow and Tsareena. With the arrival of the four Guardian Deities on Poni Island, Kiawe went out of the aircraft and started to battle the Ultra Beasts. He confronted Pheromosa, and had his Marowak use Inferno Overdrive Z-Move, which defeated Pheromosa.