Creating a bad metagame doesn't make a player lose more often. If we suddenly dropped mewtwo into OU it wouldn't make a good player suddenly lose every match, cause every player has access to mewtwo and a good player presumably can attack the metagame in a smarter way. That being said, mewtwo should definitely be banned, just as sleep clause shouldn't be removed. If you're saying sleep clause should stay because you haven't lost a game yet, I'd reconsider how you suspect things. Also consider that many players (myself included) don't know sleep clause is removed, either because they don't go on the forums or don't know what sleep clause is. I'd say suspects should be evaluated on terms of how they affect the metagame, not on your ability to get passed the suspect.