I mean, even the power of smelling really bad could have its effectiveness. I know I’ve smelled my share of things that momentarily rendered me unable to function properly. I want to say stuff that triggers the old gag reflex but technically that only comes from a physical touch to the back of your throat (pharyngeal reflex aka laryngeal spasm) or so I’ve read. The word I’m looking for that a bad smell can cause you to do is to retch (aka dry heave). Another helpful thing about making a super-villain retch, is that you cannot talk while retching, and this would cut short the typical comic villain’s long boring speech of how he came to be and what his diabolical plans for the world are.