Inhumanoids (1986)

Earth Corps, a team of scientists specializing in subterranean exploration, would prefer to simply go about their work. However, this changes when a horde of monsters from below called Inhumanoids, collaborated by the evil human traitor, Blackthorne Shore, begin to attack the surface world. Against this threat, the team, and allied monster species they meet are forced to oppose them with whatever skills and equipment are useful.