Royal is strong because the way they play would make you think they should be losing, but they often have equal gold amounts.
Plus, they often put a hyper carry in their team (usually Uzi), and then surround him with strong mid game brawlers that still scale decently well into late game, then force teamfights to bring mid game earlier. Using the teamfights, they try to push Uzi's gold to late game levels, so they bring their hyper carry into the game faster, then just strangle every lane with a strong roam. It's quite a strong strat, and the way you beat it is not incredibly evident. Either it's hard shut down early, or early inhibs to force objective play.