One of the special abilities of the Ankoku-seijins is their ability to eat light energy. However, this ability does have its limits, and eating too much of the light will cause them to explode. Ankoku-seijins also have blades attached to their arm bones, which they can extend to attack their opponent. Another ability of the species is Prehensile Feet, which allows them to hang upside-down from caves on their homeworld, similar to bats.
The only Ankoku-seijins who appears in the manga/anime series is Yakon, one of Babidi's Majins. Using the special abilities of the race, Yakon ends up eating too much of Goku's Super Saiyan aura and explodes.
In the video game Dragon Ball Z: Buu's Fury, the Mini-Yakons are miniature versions of Yakon who appear to help him in battle on the Dark Star. They can extend their tongues to attack their opponents.