Answer: nemeses

AnswerCrossword Clue
NEMESES

Formidable opponents

NEMESES

Unbeatable foes

NEMESES

Usually unbeatable rivals

NEMESES
They can't be beaten
NEMESES
Unbeatable rivals
NEMESESLuthor and Brainiac, to Superman
NEMESESThey're unbeatable
NEMESESBatman and Robin, to Riddler
NEMESESMortal enemies
NEMESESBanes
NEMESESBatman and Superman, to villains
NEMESESThe Yankees, to the Red Sox
NEMESESTough opponents
NEMESESUnbeatable opponents
NEMESESArchenemies
NEMESESBete noir et al.
NEMESESWaterloos
NEMESESArchrivals
NEMESESLuthor and Zod, to Superman
NEMESESAgents of retribution
NEMESESBaddies
NEMESESThey're unconquerable
NEMESESRuins
NEMESESThey can't be beat
NEMESESRelentless avengers.
NEMESESAvenging agencies.
NEMESESEmbodiments of retribution.
NEMESESAvengers.
NEMESESInflicters of retribution.
NEMESESAgents of retribution.
NEMESESRetributive fates.
NEMESESJust punishments.
NEMESESInflicters of tribulation.
NEMESESFates.
NEMESESJust retributions.
NEMESESJust deserts.
NEMESESRetributions.
NEMESESAvengers
NEMESESRivals to who one always loses
NEMESESSee men's foes