Re: adventure ideas?
Here's an idea, if we're talking about powered armor and such:
Some high-tech villain or organization has finally had it with the heroes' interference. They put all their plans on hold while they develop and execute a plan that will not only keep the heroes out of their hair, but local law enforcement, too.
They design and build robots whose appearance, powers, tactics, and special effects mimic those of the heroes perfectly (or almost perfectly, well enough to fool all but the most observant investigative reporters and cops, anyway). Then they turn the robots loose on the city, and a highly publicized crime wave ensues. Eyewitnesses testify that it's the heroes who are doing all the plundering: "I know it's Metal Man! He was using the same solar blast I saw him take out all those VIPER agents with at City Hall last spring!"
Obviously, with both the police and the press after them, the heroes can't go out in costume until this situation is resolved.