But anyone who uses Dory knows to save it until your counter is dead. Particularly for stall teams it's difficult because there are so many times where my gliscor or skarmory are either killed by crit stone edge from the likes of terrakion, landlos etc or so weakened after dealing with them that it isn't difficult for dory to come in and clean up. What makes it worse is that if it's a full HP balloon dory, it can still get past pokemon like gliscor/skarm if it gets a flinch on rock slide.
By that logic, CM Jirachi could be broken because a team could wait until anything that beats it is dead. You're right that a good Doryuuzu doesn't act stupid (like switching in on Hitmontop lol), but in the same way that they keep Doryuuzu in the wings, you could keep your Azumarill (or whatever) in the wings.
Then again, a good player would probably force you to resort to Azumarill (or whatever) at some point. So it can really go both ways. I'd say it depends on the skill of the players and team match-ups. Whoa. That statement actually makes it sound pretty broken.
If a pokemon can be broken, I know that it should be considered broken every time. But I'm saying it's not broken because I (a single Smogonite among hundreds of us) haven't had problems with it. I understand that I=/=anyone else. However, I have nothing to draw on other than my own experiences and those I talk to.
One last thing. Any pokemon can sweep with enough hax. Granted that a 30% flinch chance isn't too bad. It's much better than getting a crit, anyway. But if hax gets it past its counters, that doesn't really make it broken.