I'm having issues with the last boss as well, not even on NG+. I probably spent 2-3 hours on him today, and got him to 15-20% a few times. I got annoyed by the Player Message frequency when I picked up Bloodborne at launch, so I've been playing offline and trying to do all the bosses solo.
I have a few pieces of advice that have helped me get closer, though I haven't gotten the kill yet.
1) Consider stocking up on Potions/Paper, manually saving to your PS+ cloud, and then turning off auto-uploads. This way you can just manually download your save from the cloud after a dozen attempts if you run out of potions, rather than having to farm again. I only needed to re-download the save twice for 2-3 hours of attempts.
2) Play cautiously, but close to the boss. I found that I always regretted going for more than 1-2 attacks, and that he was much easier to dodge if I strafed him in circles close up.
3) Take breaks. I always had my best attempts after getting up and taking a breather.
I'm done for the night, but I'm pretty confident I'll have it soon. I shudder to think of what these bosses are like on NG+....
I have a few pieces of advice that have helped me get closer, though I haven't gotten the kill yet.
1) Consider stocking up on Potions/Paper, manually saving to your PS+ cloud, and then turning off auto-uploads. This way you can just manually download your save from the cloud after a dozen attempts if you run out of potions, rather than having to farm again. I only needed to re-download the save twice for 2-3 hours of attempts.
2) Play cautiously, but close to the boss. I found that I always regretted going for more than 1-2 attacks, and that he was much easier to dodge if I strafed him in circles close up.
3) Take breaks. I always had my best attempts after getting up and taking a breather.
I'm done for the night, but I'm pretty confident I'll have it soon. I shudder to think of what these bosses are like on NG+....