Flagg is averaging 18.8 points, 6.4 rebounds and 4.1 assists a game for the Mavs, who at 19-27 rank 12th in the Western Conference.
Three seven-player teams of NBA rookies and second-year players and a fourth of talent from the developmental G-League will play two games to 40 points on February 13 in Los Angeles during All-Star weekend festivities, with the winners meeting in the event final, which goes to 25 points.
The 11 second-year players and 10 rookies selected by NBA assistant coaches will be drafted onto three teams on Tuesday with the G-League squad chosen by the league office.
Former NBA Hall of Fame players Carmelo Anthony, Vince Carter and Tracy McGrady will each guide one of the clubs with Austin Rivers, a former player now serving as a television commentator, will coach the G-League team.
Other rookies selected include Philadelphia guard V.J. Edgecombe of the Bahamas, Russian guard Egor Demin of Brooklyn and Americans Dylan Harper of San Antonio, Kon Knueppel of Charlotte, Cedric Coward of Memphis, Derik Queen and Jeremiah Fears of New Orleans, Tre Johnson of Washington and Collin Murray-Boles of Toronto.