Hmm. The serious natured kyurem i got had the characteristic "capable of taking hits" which is frame 153. It had the right IVs as well. When I got the Timid and naive spreads, I think I was advancing like 60 times.
I tried an experiment to see how much the frames will shift with minimal time out of the menu screen.
with 0 advances, and strait to pressing A at the kyurem, I got timid, capable of taking hits
with 1 chatot cry, i got timid, capable of taking hits
with 3 chatots, i got timid, mischievous
i am more confused now though