The Hornets view Plumlee as a player who can help improve their rebounding. However, the 28-year-old is averaging just 2.6 points and 1.7 rebounds in 32 games this season, below his career averages of 5.2 points and 4.8 rebounds.
"We are excited to add Miles to our roster," Hornets general manager Rich Cho said in a press release. "He is an athletic big man who brings additional physicality and rebounding to our frontcourt rotation. He's a proven player with a strong work ethic and we think he'll fit in well with our core group."
Hawes, 28, is averaging 7.3 points and 4.2 rebounds in 35 games this season. The 10-year veteran has career averages of 8.8 points and 5.8 rebounds.
The 30-year-old Hibbert is averaging 5.2 points and 3.6 rebounds in 42 games for Charlotte. The two-time All-Star has struggled in recent seasons but has career averages of 10.1 points and 6.4 rebounds over nine NBA seasons.
Milwaukee also requested waivers on forward Steve Novak in a corresponding move. Novak, 33, has played in just eight games this season.
"Spencer and Roy are two proven NBA centers who give us additional depth and versatility in the frontcourt," Bucks general manager John Hammond said in the press release. "The trade also gives us future cap flexibility as we continue to shape our roster. Miles and Steve are true professionals both on and off the court, and we wish them all the best."