I think the Sith take it on part of superior power. Thanaton or Wyyrlok can conceivably oneshot Drallig or Solusar, Vodo is strong and Zallow is a proficient duelist but Wyyrlok is just as skilled in bladework (holding his own with Krayt) and more powerful in the force than Vodo. Zallow and Thanaton might be close, they're on the same skill tier/ but Thanaton outclasses him as a force user. The two Jedi powerhouses would fall to the darksiders, or if situations change Jerec can still beat Drallig and Vergere can take Solusar or hold him off imo