Hmm. Maybe they have the now required standard issue work uniform sentai heroes run around in before they henshin only a uniform that's equipped with this teched out badge that they either press or remove to henshin. It would form a helmet and gloves and perhaps some armored parts as well as fitting tighter on the body than it does in it's standard mode.
This is an idea I was sort of messing around with back when DekaRanger was on because I kinda liked the design and color scheme of their work uniforms a bit better than their actual suits so I was trying to imagine what it would be like to have the same thing with the mostly black suit, the star, the stripes but made as a actual sentai hero costume. I never got around to actually trying to sketch it out though..