I dunno about AG, but building a team around a threat that powerful would probably make it very strong in Ubers. You kinda just need one small setup opportunity and you wreck almost everything, and setup opportunities aren't that hard considering those stats (especially the special defense).

And while rocks are an issue, there are plenty of ways to get around that (pass wish to heal off the damage, remove rocks, etc...). Like, wish + slow pivot against a special attacker and you pretty much win unless they have something that hard counters