The most boring and time-consuming part of creating NPCs and monsters in the BRP family is calculating all the skills based on the stats and what they mean. I stopped actually doing this a while ago, and instead use a concept I called "competence bands" to quickly determine what percentage an enemy has to succeed. Here are the basics of it.
I sort all enemies into five rough measurements of competence and power that are each given a numeric rating
5: Demigods, anyone who can be described as "the greatest X in the land", epic world-threatening monsters (the Titans); top-level badasses in whatever field
4: Famous warriors, big bads, monsters of mythic scope and power (e.g. the Lernean Hydra, Cetus), masters and highly respected experts of their professions, people you'd journey across a kingdom to seek out the advice of, or to recruit to your cause
3: Professional, veteran warriors, tough monsters you'd encounter on a wandering monsters table (e.g. Ogres), professional artisans and other experts, leaders of bands of weaker foes
2: Competent troublemakers (bandits), ordinary predators, unintelligent monsters, ordinary people practicing their chosen trade
1: Creatures that rely on numbers instead of skill, incompetent individuals, students or noncombatants
When one needs to figure out the skill rating for a particular test, one merely needs to answer the questions "Is this part of the person's specialty, a weakness or neither?"
Part of their specialty: The skill's rating is the numeric rating x 25
A weakness: The skill's rating is the numeric rating x 10
Neither: The skill's rating is the numeric rating x 18
Here's the math predone for you: It goes Rating: Specialty Skill Percentage / Non Specialty Skill Percentage / Weakness Skill Percentage
5: 125 / 90 / 50
4: 100 / 72 / 40
3: 75 / 54 / 30
2: 50 / 36 / 20
1: 25 / 18 / 10
If you need something more fine grained, creatures have a number of specialty skills equal to their numeric rating. 5s have 5 specialty skills, 4s have 4 specialty skills, and so on. I recommend giving all opponents at least one weak skill. You may wish to try giving them (5-their numeric rating) weak skills, but I find this a bit fiddly for personal use. YMMV.