Ariza, 33, averaged 9.9 points, 5.6 rebounds, 3.3 assists and 1.5 steals per game in 26 appearances this season for the Suns. He signed with the Suns as a free agent in July after spending four seasons with the Houston Rockets.
The 6-foot-8, 215-pound veteran played for the Wizards for two seasons before joining the Rockets. Ariza won a championship in 2009 with the Los Angeles Lakers. He is a free agent after the season.
Oubre, 23, is also a free agent this offseason. The 6-foot-7, 205-pound forward was the No. 15 overall pick in the 2015 NBA Draft. Oubre has played his entire career with the Wizards. He averaged a career-high 12.9 points and 4.4 rebounds in 29 appearances this season for Washington.
Rivers is averaging 7.2 points, 2.4 rebounds and 2.0 assists per game this season. The No. 10 overall pick in the 2012 NBA Draft was traded in June from the Los Angeles Clippers to the Wizards in exchange for Marcin Gortat. He is also a free agent this offseason.
The Wizards host the Lakers at 6 p.m. on Sunday at Capital One Area in Washington, D.C. The Suns battle the Minnesota Timberwolves at 9 p.m. on Saturday at Talk Stick Resort Arena in Phoenix.