Okay I may be stepping in it, *but* here's the dilemma:
Skeletal minions via animate (or animate, lesser) are mindless.
Mindless creatures have no feats.
Here's the issue:
Skeletons retain weapon proficiencies-which are feats. As well as there's a mention of skeletons wearing armor (also feats), and then there's the skeletal archer, whose entry refers to the skeleton template, but it has two additional bonus feats.
The skeleton template though states all feats are lost but improved initiative, which is a bonus feat.
"Archer" is not a subtype of skeleton, "skeletal archer" is not a template. It's a creature.
Do skeletons get feats (armor and weapon proficiencies, weapon/combat related bonus feats) or not?
Are they skilled with weapons? Are they skilled with armor? Can a skeletal archer actually have point blank shot and precise shot? Is it considered a variant skeleton, even if it isn't a template?
Weapon proficiency are not feats. Sure, you can gain proficiency with weapons from a feat, but the class proficiencies aren't giving you dozens of bonus feats.
You'll notice that the various proficiencies are never included in a creatures feats line in its statistics, because they aren't feats. Only those proficiencies gained by taking the feat are feats.
Let's be clear. Skeletons and zombies can have a few feats, but they are only BONUS feats. Skeletons get improved initiative and zombies get toughness. They can, with some other templates, get other feats specific to that form/template.
Mindless creatures "gain no feats or skill points." This means they never gain those things as the result of leveling up. No matter how many HD they have, they won't have any skill points and can never "learn" feats. They can, however, have bonus feats which are determined by the template, which can't be changed.