Using your Blaziken as a reference, I was able to dissect the data and determine what they correspond too:
Not gonna lie, it is a bit more than what I thought it would have been, but most of them (such as relevant stats) being there makes sense, since those are needed for battle.
It would have been nice if Origin Data and Met location was there (needed for legality), but we could always make educated guesses for those.
With this I can go ahead and extract the 3 mons of hers (as far as I can tell, only 3 mons per mixed trainer are stored). Probably may make a PKHeX plugin down the road so we can see the other mons of mixed trainers.
So notably, the stuff that is missing from the data structure are:
Language, misc flags, markings, PP bonuses, friendship, contest stats, pokerus, met location, origin info (location, ball caught in), ribbons, fateful encounter flag.
Edit again: I’ve made good progress with my building my plugin. I’m able to send all the data available for the Mon to PKHeX ‘s viewer. It’s technically workable as it is but I’ll like to see if I can bake in PKHeX legality features.