There was the Pneumatic Man and the Wind, both blowhards literally as well as figuratively, using compressed air as defense against the Battling Bowmen.
A step up was Red Dart, who would years later face Green Arrow, while the Blue Lancer had but one sole appearance dueling with the Arrow.
Finally, we have Camouflage King, who discovered a disappearing paint to assist his criminal schemes vs the silver age Arrow. On the flip side, there was the Black Magician who had to rely on slight of hand tricks to make things disappear in the golden age.
And we're just scratching the surface of decades of devious dorks...