Gliscor is a large, mainly blue-purple vampire bat-like Pokémon, partially clad in an insect-like carapace. Its legs have two toes and a slightly darker circular coloration on the underside, and its tail has two barbs, giving its tail the resemblance of a vampire's fangs. Its arms are red with thin striations and are completely detached from its black wings, and each is ended with large pincers. Its ears have discernible, red, chambered ear insides, and its eyes are yellow. It has six visible fangs in its mouth, and its waist, like its arms, is red and striated. Gliscor's body resembles an open mouth, with the pointed protrusions coming from its upper torso resembling fangs, further illustrating its vampiric qualities.
Gliscor feeds on the blood of other Pokémon species; biting their necks with its long, sharp fangs. It is even said to take pride once its prey is fully drained of blood. As shown in Riding the Winds of Change!, Gliscor, along with its unevolved form Gligar, can emit a sort of sound wave in order to detect obstacles and fly around them, similar to echolocation. Its legs appear to be not suitable for walking, so it can only perform short hops when on the ground. Gliscor hangs upside down while sleeping, much like other bat-like Pokémon, and it is nocturnal. It is capable of soundless flight; however, its wings cannot be flapped to the same extent that other Pokémon's wings can. Like Jumpluff and Wingull, Gliscor uses winds and updrafts to glide from place to place. When there is no wind, Gliscor climbs to the top of tall trees using its sharp raptorial claws and then glides from place to place. This practice is similar to flying squirrels. Gliscor is highly resistant against poisonous substances. It is extremely rare, but sometimes it is found in thick pine forests, swamps, and even alpine regions.
Gliscor is lighter than its pre-evolution, weighing in at only 93.7 lbs. (42.5 kg), while Gligar is 142.9 lbs. (64.8 kg). This is despite nearly doubling in size during evolution, from 3'07" (1.1 m) to 6'07" (2.0 m).
Gliscor can be seen as a parallel to Weavile. Both were introduced in Generation IV, both of them are dual-types, have the same base stat total, have Special Attack as their lowest stat, have double weaknesses (Gliscor to Ice, Weavile to Fighting), evolve from Pokémon that were introduced in Generation II, and do so by leveling up at night while holding items that contain the word "razor" (Gligar evolves with Razor Fang, whereas Sneasel evolves with Razor Claw).
Gliscor appears to be based on a combination of gargoyles, scorpions, and vampires, which in turn share traits with bats. It may also be based on the scorpionfly. Additionally, it shares features with the amikiri, a yokai with lobster or scorpion claws and the ability to fly.
Gliscor and Glion may be a combination of glide and scorpion.