Dialga and Palkia were easy for me to catch. I knocked down their HP into the red zone and had them paralysed. Compared to other legendaries, they are the second easiest to catch, with catch rates of 30.
Catch rates for the two Dragons are high compared to the rest of the legendaries. Which is why Giratina was a kick in the teeth to catch in Platinum compared to the other two. Now the roaming birds... now that's a pain.
I was expecting it to be hard since I saw so many Dialga and Palkia on Masterballs at GTS. But when it came, two ultra balls were necessary to capture it. No status change and HP slightly on red.
What pokemon is worth Master Ball on DP generation?
I would say Cresselia, Zapdos, Articuno, Moltres and Mesprit.
Uxie and Azelf were a pain in the ***** for me but Dialga and Palkia were extremely easy, even at lv.70!