I have heard many different findings. However, unless you open sealed cases, you really can't make an accurate assesment. I think or would hope that it is the following -
Shinings - I want them to be 1 per 3 boxes, but I expect they are 1:2.
Charizard Line - I would also hope they were 1 per 3 boxes, but I expect they are closer to 1:1 or 1:2
Lv. X - I want them to be 5 for every 3 boxes. I am not sure on this. I would expect they are but it wouldn't suprise me to hear that it is 1 per box.
I can't say one way or another until the set is released next month.
Drew