Yes, fenders for sure, and ones with mudflaps in the front, as I recently learned. But beyond that any bike with fenders would serve as a rain bike, or just a bike that can be ridden in all weather conditions. All other criteria are not so much weather-related as it is really personal preference, or perhaps terrain related--IGH vs geared vs SS, road bike vs hybrid vs mtb vs dutch-style, caliper vs linear pull vs cantilever vs hydro, etc. Yes, disc brakes are best for wet conditions, but unless you're racing crits I don't see a huge benefit to them. I don't recall ever having to make an emergency stop that my calipers or cantis couldn't handle. Maybe if I were stronger ride who rides 25+ mph all the time I would feel differently.