There are individual world rankings for 3x3 basketball as well as national rankings for individuals and a National Team must include a minimum of 50% (2 players) who are within the top 10 players in their national rankings - I they are trying to distinguish 3 x 3 as a distinct sport on the international level and not just have 5 x 5 players parachute in for the big competitions. The National individual rankings are based on the ten best tournament scores played by the individual during the past 12 months including national, regional, and worldwide tournaments.
This is the 2024 Fiba 3 X 3 handbook with the various requirements for participation, etc.:
I believe other sports have similar kinds of qualification requirements for individuals and teams based on their International federations.
