The Death Busters are very practical. After they feed on the souls of Mugen Gakuen students, they even have a use for the bodies left over. They use the bodies as vessels for daimons.
You see, after a student is convinced (by one of the Witches 5, probably) to dedicate their body and soul to the Death Busters and to Pharoah 90, their soul is taken to provide energy for Pharoah 90. Then Professor Tomoe plants a daimon inside the body of the unsuspecting student. The student will look, act, and think perfectly normally... until the time comes when the daimon is needed.
Whenever Kaolinite or one of the Witches 5 needs help, they can summon a daimon out of the student's body to help them fight the senshi. With the words "Daimon Power!" a daimon will burst out of a student's body, leaving the student lying in a faint on the ground. Daimons are easy for the senshi to defeat, but they are still frightening.
Daimons do not necessarily have to be planted inside a student, but that seems to be the best way to transport them. Professor Tomoe creates them in his labs, and Ami caught a glimpse of them when she sneaked into Mugen Gakuen's basement. Professor Tomoe keeps them in cages, but occasionally, one escapes and rampages about the neighborhood.
In general, daimons tend to look like huge black slugs with teeth, tendrils, and glowing eyes. They also leave behind a trail of black slime when they move.