Huh... What Lib4ris Mortis has to say about it:
"When you create a character at 1st level, roll ability scores normally, including assigning a score to Constitution. Because the character is undead, however, the character is treated as having no Constitution score."
...
So we are on the honor system for ignoring the obvious dump-stat...
There is the awaken undead spell too, it is kind of awkward, doesn't seem to say anything about it for character creation...
Oh! It is also in the spell compendium, I think that the D.M. has that one, page 21.
...
Huh... I could have sworn that there was a level adjustment, or at least a CR modification, on
awaken.
I would consider imposing a forced expenditure on constitution, maybe 4 or 6 points, it would be relevant if the undead came to life for some reason...
Libris Mortis also says to create the character normally and then apply undeath to it.
Lich is a good comparison:
Lich/Skeleton
paralysis/1claw per hand
Paralysis seems more powerful, only once per round though...
Fear aura/-
Mostly used to set up an early sense of foreboding for a late-game character. Could clear our some henchmen or hirelings or that army of dogs that the players brought with them...
Turn resistance +4/+2
Lich wins...
DR 15\bludgeoning and magic/5\bludgeoning
Lich wins...
Immunity to cold, electricity, polymorph, and mind affecting/ immune to cold, not specifically immune to mind effects, but it is redundant with undead...
Lich wins, electricity seems a little on the rare side, and polymorph is very rare, but very nasty...
int+2,wis+2,cha+2/dexterity+2,int*=1d6+4,wis=10,cha=1 *int cannot exceed living int
Assuming that these can be increased due to stat allocation, keeping with the 'even ability modifiers' rule, and cutting out the randoms, skeleton would be dex+2, int -2, cha-10(min 1) and ability buy would occur as normal with those modifiers. Given that undead are immune to most ability loss, and skeletons receive a huge circumstance penalty to social skills in most societies, all charisma means to most classes is a lack of Use Magic Device potential. I would consider it more like a -2, -4 tops for balance purposes... Lich wins, for sure, but skeleton is still better for most non-casters...
+8 racial to 6 skills/-
Quite a nice bonus for the lich.
LA +4/?
Oh, one last thing, the skeleton's intelligence is dependent upon a 6th level cleric domain or 7th level sorcerer/wizard spell with a duration of permanent, if you are dispelled you become an N.P.C. until you can get the spell cast again...