Aminu, 31, is 6-foot-8 and an 11-year veteran who was waived by the Spurs in training camp. He appeared in 23 total games with the Bulls and Magic last season and carries career averages of 7.5 points and 6.0 rebounds.
Pelle, 28, is 6-foot-3 and has been playing with the Cleveland Charge of the G League, averaging 8.9 points, 8.3 rebounds and 1.1 blocks. He has spent time in the NBA with the 76ers, Nets, Knicks and Kings.
The Celtics have eight players in health and safety protocols, including a large chunk of their frontcourt. They face the Bucks on Christmas Day.