That's a hard one. We have no idea what kind of effect chaos emeralds would have on Equestrians. You see, all ponies of Equestria are magical in nature. Earth ponies have innate, instinctive magic that happens on it's own. Pinkie pie, for example, can predict the immediate future [link] . Add chaos emeralds to that and anything could happen. Another reason this is difficult is because "cupcakes" Pinkie is not a slayer, warrior, or spree killer. She's a serial killer. She doesn't directly attack her victims. That would be stupid. She stalks them, learns their strengths and weaknesses, attempts to establish trust, and only then does she make a move (usually with sedatives, tranquilizers, or narcotics/hypnotics). Under ideal circumstances, the victim wouldn't realize there is a danger until it's too late ("So what now?" "Now....you take a nap." "Huh!?"). And Shadow, he distances himself from everyone. He's anti-social. Chances are he'd never interact with pinkie in the first place. So this isn't really a good match up. It's kind of like Gladiator vs Ninja. A Ninja wouldn't fight a Gladiator. He'd make himself "disappear" and wait for an appropriate time to strike. If the Gladiator never drops his guard, the Ninja would never strike. Stalemate