My player has chosen this mystery, and has been using it similar to how a Summon Monster spell might be used (lasts a couple rounds, gives a chance for flanking, a little bonus damage, etc).
The problem is, it's a lot of work statting up a full creature from scratch each level, that's going to be used once a day for 3-4 rounds.
See, a Summon Monster spell points to a fully stated creature entry, and at most requires slapping a celestial or fiendish template (adds a couple things you can remember off the top of your head).
You know it's appropriate for the level you are casting the spell at, because it's based on creatures of a certain CR.
The problem we run into with the wording of the "Raise the Dead" mystery, is that it just says "skeleton" or "zombie". If you really take a good look at those creatures.. they are really just templates. They are supposed to be applied towards another creature, and slap a CR+1 onto it.
I've so far ruled that it's the standard humanoid from the starter stat block (basically a 15 Str and 12 Dex base with modifiers), and then just added HD as per the oracle's level.
The problem is that there are no size increases, no stat increases, no natural armor or weapon increases... no added abilities or special attacks, etc.
I used an excel sheet to quickly stat out 20 levels of a normal skeleton or zombie, and with the advanced and/or bloody/fast templates.
What we end up seeing is that after a few levels, even with the added templates, the damage and AC are ridiculously pathetic (the other stats are mediocre to pathetic, but they at least scale with the HD somewhat).
I mean.. is the 20th level Oracle's skeleton supposed to still be doing Melee: 2 claws (1d4+4)? With an AC of 20?
Or the zombie with Melee: 2 slams (1d6+7) and an AC of 16?
Yes, those are with both templates being added to each.
With saves in the 8-12 range, and an attack roll (not BAB, the total attack roll modifier) of 17-20... what exactly is the role of this thing?
Fast Healing 10 or 40' movement simply do not cover the useless stats these creatures have.
If it's not meant to be used like a summon monster.. then it's kind of misleading. It starts off as being "decent" for that purpose for the first few levels, but then around 5th and up it's practically a wasted action. It's almost guaranteed to get hit by attacks or spells/abilities, and nothing will care about it's attacks anyways (won't even do enough damage to get over some DRs!), so it's what... a few rounds of flanking bonus?
I can't believe that's the only intended usage.
.
Now, I'm not one to complain or criticize without giving some kind of constructive thoughts...
I've thought about simply applying the skeleton or zombie template to the animals in the Summon Monster list... however it results in a fairly large chunk of math reworking.
Perhaps a short list (similar to, but shorter than the Summon Monster list), of creatures you are okay with seeing as appropriate per level of Oracle.
Basically, a list of things that you can apply the skeleton, zombie or bloody/fast/advanced templates to. Starting with Humans and Wolves at the low levels, and dire crocodiles or tyranosaurs at the higher levels.
Alternatively, you could simply write up a stat block from 1 to 20. Give it natural armor, str/dex scores, and natural attack damage that is appropriate for the level.
It would look kind of like the Eidolon stat chart, except that it's even easier since it doesn't have skills, feats or special abilities (other than fast healing or increased speed/slams).
The second one would keep it the most like it is now, and keep it a bit more viable (attack, ac, damage and saves being more in line with what it'll be used for).