Potency: How impactful and entertaining they are to watch in a base sense. Simple characters tend to have a disadvantage at the other two ratings, but do have an advantage here as their simplicity often gives them an ability to be exaggerated and forceful. Basically potency is how much presence a character has, how much they steal the show when they are on screen. A character with a lot of potency makes every scene they are in larger then life by their presence. A character with a low amount of potency can be kind of dull and can't hold attention alone. An example of a character with A LOT of potency in my view is Panty Anarchy from Panty and Stocking with Garterbelt, who has a very entertaining forceful personality that causes a big impact. Can also be seen as how well-done the character archetype is expressed.
Versatility: How many situations can this character be a part of? Can they fit into a large variety of plots and settings? Can they interact with a large amount of characters? Versatility is a measurement of how well the character to a large amount of possible milieus, how many different moods and atmospheres they can pull off. Characters with a lot of versatility are more archetypal and can shift to a suit a variety of contexts. Characters with a low amount of versatility only make sense in the very specific context of a singular story and thus can't be reinterpreted or don't offer much to think about. An example of a character with A LOT of versatility in my view is Aku from Samurai Jack, who is a very archetypal character that can fit in a large variety of moods, settings and plots. Can also be seen as how good the character's archetype is and is expressed.
Compelling: Often, but not always this is the same thing as "Depth" but a character can be not very deep but still be very compelling. Compelling is a measurement of both how well-realized and how sympathetic a character is, often which goes hand-and-hand. A very compelling character is a character who is very understandable in their desires, who has a lot of good reasons for what they do, and have goals that make sense given their personality and story. An uncompelling character comes across as flat, stereotypical and often either irrational or just unpleasant to watch. An example of a character that is VERY compelling in my view is Duck from Princess Tutu who has clear very sympathetic goals and motivations and which you greatly want to see succeed. Can also be seen as how well-integrated the character archetype is into the story.
If you imagine that each character starts with 1 point and that I give additional points (0 for Bad, 1 for Boring, 2 for Good and 3 for Great) for each of these 3 you can see how I rate them out of 10.
1/10: Bad in every category. A Boring confusing mess of a character.
2/10: Mostly Bad. Character is not fun to watch at all but is no longer as painful to watch.
3/10: Worse then Dull (Unpleasant). Character generally is inconsistent or has one area of weakness but otherwise is just boring.
4/10: Dull. No strong feelings towards the character
5/10: Better then Dull (Fine). Character is just alright, usually has one particular category I think they are good in. Is fine for a minor character. About 45% or higher of characters are here.
6/10: Worse then Good (Mostly Good). Character is good in at least two categories generally. Generally the character has definite strong points but is not usually my favorite in a series, unless it's a poor series. About 45% or higher of characters are here.
7/10: Good. Character generally is good in all categories, the character is consistently enjoyable to watch in all 3 ways. I think the character is cool and admirable. Often one of, if not my favorite character in a series.
8/10: Better then Good (Really Cool). Character is good in two categories but has one specialty where they are great in (or has two areas they are great in but one they are dull in, which is surprisingly often). Characters here are real-stands out for a series generally, not just in the character department but in general one of the best parts of the series. Some of the characters in my top 100 characters were here so it's really getting into the top tiers of fiction quality-wise imo.
9/10: Mostly Great. Character is great in two categories and good in the final. Character is a joy to watch and is easily one of my top tier characters of all time, something to be replicated. 9/10 characters I get really excited to talk about and can easily be a good main character of their own series if they aren't.
10/10: Fully Great. Awesome. Character is great in all 3 categories, a nigh-unprecedented achievement. So far there have been 6 characters I consider 10/10 (1 of which is a villain). Such characters are great enough that they could and should in my opinion change fiction as a whole, and set a model and precedent to be imitated.
For Villains specifically there is a separate 3 categories, though compelling remains. They are Threatening, Entertaining, and Compelling, which seem relatively self-explanatory by now. That said the scoring works in a similar way.