William A. Barton reviewed Opponents Unlimited in The Space Gamer No. 63. Barton commented that "Though its usefulness is lessened by its excessivesilliness, Opponents Unlimited could be of value to those V&V GMs who don't have time to create their own villains and don't mindtossingopponents named Cosmic Zoom, who wear deep-sea diver's gear, at their heroes. I guess it all depends on which comics you read."