Yeah, though don't forget that Tentacruel and defensive Mega Venusaur also beat the set as well (which are both handled by Extrasensory as The Big Aristotle just slashed with Dark Pulse on the set above). Greninja is pretty crazy though and is extremely difficult to switch into. Strong priority (Talonflame, Mach Punch users, CB Dragonite) and the fast Megas like Sceptile, Manectric and Beedrill keep it in check offensively but it's hard to keep Pokemon from taking severe damage or dying when Greninja is on a slower Pokemon. Plus, switching out doesn't have much of a cost for it since it has no need to set up at all.And KyuB.
Anyways, I have been watching a buddy of mine use the Ninja Set posted by Jaguar360 a couple pages back (I refuse to use this tumor) and I've gotta say, that thing is ridiculous. By far the best set I have seen this thing run. It 2HKOs the entire metagame outside of P2, while being nearly impossible to freely switch into.
In short, it's absolutely ridiculousand just goes against Ninja's case of not being borderline borked.
Hydro Pump is still useful, as it is pretty handy to have on Spikes sets and is Greninja's strongest move aside from Gunk Shot, which is a bit stronger with full investment. However, I do agree that it is not as necessary as it was in the past, as Gunk Shot + Ice Beam + coverage reduces the need for it by a lot.I'm very anti-Hydro Pump at this point, and I see very little reason to run it. Ice Beam and Low Kick cover pretty much everything it used to hit, and you don't have to deal with HP's shaky accuracy either. I think the standard Ninja set should be (and probably is, by now):
Gunk Shot
Ice Beam
Dark Pulse/Extrasensory
Low Kick
...So basically the set Jaguar posted, but with Extrasensory slashed for stuff like Tentacruel and Conk. I'm really starting to wonder whether or not this thing is getting too powerful for OU -- at this point, I run T-Flame on basically all my teams as it's the only surefire way to check it in this meta.