Shams Charania of The Athletic and Stadium reported Ellington is likely to be waived.
Anderson, 30, is averaging a career-low 3.7 points per game and hasn't played since early December. However, the stretch 4 has averaged 12.5 points per game in his career.
Johnson could hit free agency this offseason, but as Zach Lowe of ESPN noted, it's assumed he'll pick up his player option for $19.3 million.
The guard is making more than $19 million this season and has a 15 percent trade bonus worth $1 million, according to Bobby Marks of ESPN.
Originally an undrafted free agent in 2014, Johnson has spent his entire five-year career with the Heat. He got a big boost in salary in 2016 when the Brooklyn Nets signed the restricted free agent to an offer sheet of $50 million over four years, which the Heat matched.
The 26-year-old has had his moments since, most notably averaging 13.7 points per game exclusively off the bench in 2016-17. However, he has struggled to evolve while averaging 10.8 points and 2.5 assists per game this season.
He has also failed to take advantage of Goran Dragic's absence, as his fellow guard's missed most of the year with a knee injury.
Still, the Suns have been desperate for point guard help all season. Devin Booker has spent a lot of time running the offense, but the team needs someone who can take the pressure off its leading scorer, and Elie Okobo hasn't done that job.
Meanwhile, Ellington can help thanks to his outside shooting, as he's knocking down 38 percent from three-point range in his career. Although he is in the midst of a down year while averaging 8.4 points per game, he could improve upon that with more opportunities in Phoenix.
Adding Johnson and Ellington could provide the young Suns with additional offensive threats as the squad tries to remain competitive this year and beyond.