[3] Gaines attended Serrano High School in Phelan, California, where he played four years of varsity basketball as a point guard under head coach Mike Browning.
[2] During the season, he averaged 23.6 points and 5.2 assists per game, among the top in Southern California, and he featured in the Los Angeles Times column for his accomplishments.
[8] In his sophomore, junior, and senior seasons, he was named Mojave River League most valuable player, Daily Press Athlete of the Year, and first-team All-California Interscholastic Federation (CIF).
[9] Sources: Rated a three-star recruit by 247Sports.com coming out of high school, Gaines committed to play for the Penn Quakers on October 10, 2006.
[2] In March 2009, Gaines announced plans to transfer from Penn, later expressing dissatisfaction because they moved him to the shooting guard position.
[20][21] In April 2017, it was announced that he would be a part of the representation team for Lonzo Ball, who was projected to be a top pick at the 2017 NBA draft.
[20] Gaines had met the Ball family while attending Thomas Jefferson School of Law and was specifically picked for the job by LaVar.
[22] In the following weeks, after LiAngelo and LaMelo signed with the Lithuanian team Vytautas Prienai–Birštonas, Gaines featured in a piece for The New York Times.
[25] As of 2021, SLASH Sports has over 50 clients total ranging from the NBA, WNBA, and top international basketball leagues.