The Amori Brothers are a trio of siblings that are recurring veterans of the hunter Exams, whose speciality focuses on teamwork above all else. During the Exam Gon and the others competed in, Amori was #197, Imori was #198 and Umori was #199.
During the initial stage, Satotz's marathon, they aided Tonpa in driving off some of the weaker contestants, such as Nicholas, showing that they've known Tonpa for some time, and have likely worked together with him before.
During the fourth stage of the examination, Umori, the youngest brother, tried stalking Killua in order to claim his badge. However, Killua managed to overpower him, holding his brother Imori hostage in order to get a hold of their badges, two of which he throws into the woods, since he doesn't need them, failing the trio.
They encounter Gon and Killua again in the Heavens Arena, but are casually brushed aside by the former assassin, who seems to have honestly forgotten them. During a match, they are easily overpowered once again, eliminated with a single blow all at once from the tournament.
During the Greed Island Arc, they tended the 288th Hunter Exam, only to be easily wiped out during the first stage by Killua. Seeing the tremendous gap in potential between Killua and themselves, despite the boy's age being much younger than their own, the brothers finally decide they will never retake the Hunter Exam again.