Expert Belt
This goal requires you to obtain an Expert Belt.
It is given to you as a Battle League reward for defeating four trainers in Dalizapa Passage.
Alternatively, the Expert Belt is available for purchase at Delibird Presents for ₽30,000 as soon as you have collected four Gym Badges.
Location
Section titled “Location”The Battle League Rep that gives you this reward is located in the Cave Portion of the PokéCenter in the Dalizapa Passage.