I wanted to update this with my box information.
I bought 2 boxes. I pulled a Regigigas lv.X, Raichu lv.X, Heatran lv.X, and Shaymin lv.X. I also pulled 1 of each shiny Pokemon, 1 Charizard, and 1 Charmelon. This was EXACTLY what I expected.
I mixed up the packs to begin with, and opened them at different points, but I am pretty sure one box came with the fabled Regigagas and Raichu combo that has been seen at least 2 other times, and the other came with Heatran/Shaymin. I make a point about the Raichu/Regigigas because it reminds me of DP5/DP4 where certain boxes had specific cards. Of course, there isn't different boxes now, but I don't see how it has to be different.
The Shinies seem to be on the same level as the lv.Xs, honestly. 1 per box. I don't see why they shouldn't be treated as such. So, realistically, you can get around 2 lv.X, 1 char, and 1 shiny. If your box doesn't come with a shiny, then you probably will get another lv.X or another char. Then you have weird boxes...which do happen. Like my DP4 box that only came with 2 Lv.X and the last lv.X was a normal Leafeon instead of the Leafeon lv.X.
Holographic card ratios were decent, but outragous in some cases. I pulled 5 Regigigas holos and 5 Mismagius holos yet only 1 Shaymin. The rest of the foils I pulled around 2-4 of each.
The rares weren't bad. I pulled only 3 Gengar, which is a HUGE bummer, but I did pull 5 Tyranitar, which was cool.
I only pulled 3 Pokedrawer, yet 4-5 of the other poke-stuff. So many of that lame supporter too, which was bizzare.
Overall, I think the boxes are more concrete and static then we give them credit for. We just haven't figured out the system they use to divy it out.
B_T: Each of your boxes came with 2 chars? Did either have a shiny? If not, there is your ticket.
If I had to make a guess, I'd say that Japan is giving us Char and Shinies to make up for the 1 less lv.X we get in a box. So now we get 2 lv.X and 2 super rare cards.