Aaaand the game is too easy. Took down good ol' bridge drake pal without too much trouble.
Really? How? I've done it like five times now but the bastard still gives me trouble. It's pretty much the only boss that I consider to be genuinely hard. Or to put it another way, I still haven't found a good way to cheese him. I use the glitch that causes his big hovering-while-spewing-flame-downwards AOE attack to miss you if you stand in a particular place, but that's still not 100% reliable. If he decides to dash forward, I'm either killed by the dash attack or the follow-up.
Step 1: Give him a good ol' Gough Arrow to the face (Gough Bow +5, easy with the purchaseable titanite)
Step 2: Run up and smack him with 2H +15 Scythe running attack (very good str/dex scaling weapon)
Step 3: Back down the stairs, switch to Black Knight Shield and peek out waiting for him to stop breathing fire. The fire attacks don't do damage, but drain a LOT of stamina with the shield (black knight shield is 95% flame resistance, decent stability)
Step 4: He will sometimes bite, tail swipe or walk around and stomp. As long as he is not breathing, run out and smack him.
The trick here is to keep running out, as he will either keep breathing or will fly back. Flying back is bad, as he will heal if he is low. I think a Gough Greatbow with Gough Arrows and a Hawk Ring can outdamage that, but I wouldn't bet on it.
A good thing to know is that if you are trying to shield his flame while he flies, use autolock before blocking. The flame direction is NOT the same as what you see, and actually seems to come either from him directly (as he moves), or from his destination. Either way, if you don't know that, you will die quickly.
He used to be a LOT easier on the console on release, as he would rarely breathe fire, and almost never do the vertical breath attack. He has definitely been tuned for the PTD edition, but is still quite manageable.
If you actually want to cheese him, knock of his tail. Rest. Then keep shooting at his tail again, and he is likely to glitch and die. Just like that.
But that's no fun, no fun at all.