Originally Posted by Fat Umbreon Dan
Again, there's no reason why one would use that over Celebi, but I'm just going to point out that the spread 252 / 136 / 120 gets you a free defence point.
The only difference is that Celebi has much more weaknesses, especially being weak to U-turn and carrying a Pursuit weakness, which Pyroak isn't necessarily afraid of.
Celebi can't really hurt Tyranitar and Gyarados either, since it will fall under a 2HKO with Crunch or an OHKO with a boosted Bounce (assuming Reflect is not up). Pyroak can at least burn them to lose their effectiveness.