if your looking for other cichlids you could try fiemouths, salvini, severums(but if the oscars truly evil this might not be the best), jack dempsey, blackbelt, chocolate, acara, green terror(maybe), T-bar, tilipia joka(they stay small), any pike cichlids that would stay smallish.
and i'm sure you already know this, but try not to get any pairs of these fish cause then your oscar might be the one in trouble.