Ra is an amazing initiator/counter initiator. Basically you man up with him with massive balls and as long as you play incredibly aggressive then you can't go too wrong. That and pray they don't pick predator. Ra's starting armour is a pile of wank, and he's pure magic damage, so pred with his magic immune and high physical damage will tear you a new one.
Without wanting to toot my own horn, I made a Ra guide that I follow all the time and I can't remember the last time I lost when playing as Ra.