>>57971059
Not sure about Dot and Uruto, but Roy's team happens to consist of Pokemon with red, yellow, and black in their designs, which are all present in Roy's design. Gholdengo would be a fitting capture because of this, as well as it having the treasure theme.
I think he should also catch an Octillery since it follows the color scheme and goes with the context of his parents being out on the oceans.