I'm talking about what does that stat actually measure? With normal stats like HP and Speed, you can have some vague idea of what is being measured if Pokémon were real. Beauty, on the other hand, is far more abstract.
Actually I'd say out of all the Contest stats the most abstract one is "Cool". With Beauty, Cute, Smart, and Tough there are some stereotypes you can "rely" on to maybe help form a definition, but what stereotype does "Cool" have? As far as I know, "cool" is mainly just another word for "awesome" or "amazing", and if that's the case then wouldn't all the moves count as that as long as they're performed properly? Here's a list of quick stereotypes I can think of:
Beauty: I think the best way to describe what stereotypical beauty is desired perfection and flawlessness. There is nothing out of place, no blemishes, nothing's "uneven"; everything is as not only as it should be but treated with so much care that it could be considered the pinnacle of what that should be.
Cute: While Beauty is trying to match up to something, Cute is trying to draw something out from you: sympathy. when you see something cute it makes you want to hug it, makes you want to feel sorry for it, makes you want to protect it. It makes you not want to see something bad happen to it to where you'll probably go out of your way to make sure it doesn't.
Smart: When you're smart you have something to prove. You prove that you can solve puzzles, answers questions, and do things in a way no one else would have thought of. You can think outside the box, create new ways of doing things instead of following how it has been previously done. You're thinking 10 steps ahead while everyone else is thinking in the now or only a few steps ahead.
Tough: When you're tough you don't have anything to prove. Why? Because you're strong and if anyone questions it you quickly "enlighten" them why, that's why! You're strong enough to lift the heaviest of things, sturdy enough to withstand the hardest of blows, and have the attitude of someone no one wants to mess with.
So with all that said, what would the stereotype of "Cool" be? Leaning against a side of a wall wearing an opened jacket and a pair sunglasses?
And how does feeding a Pokemon blended berries, with or without a base Poffin batter mix, make them suddenly better in those stats? I feed my Pokemon a Pecha Berry it doesn't get any cuter, but it does if I shove that same berry into a blender?
Well for Beauty, Smart, and Tough I can see eating certain supplements helping with that. Beauty Pokeblocks/Poffin makes a Pokemon's skin/scales/shell/hair/fur/feathers look healthier, smoother, and glimmer. Smart Pokeblocks/Poffin gives your Pokemon essential vitamins and nutrients their brain needs to grow and think faster. And Tough Pokeblocks/Poffin can help strengthen your Pokemon's bones and muscles.
But I have no clue how they're suppose to help with looking cute or being cool.
It's the same thing with stat boosting drinks as with berries. With the exception of protein, how does the given vitamen directly correlate to the stat it boosts? It makes no sense.
Hmm, Bulbapedia used to have an explanation but now it's gone. Let's see what I can come up with:
Protein: A few of Protein's functions in the body is having it react and respond to stimuli, which can be related to Attack as that relies on physical movement and you'll need your body to be responsive in order for it to perform the attack correctly.
Iron: This is just for pun sake. As Vader_the_White said, Steel-types are considered THE most defensive typing so what Vitamin can be used to represent that? Iron, because we do have a bit of iron in our body.
Calcium: While Calcium is used to make bones and teeth stronger (since they're made of the stuff), it also serves the function of activating exocytosis which controls the cells use of energy. This process allows things such as neurotransmitters to release (aka let's you think), muscles to contract (aka let's you move), and is part of the heart's electrical conduction system that allows it to beat (aka let's you live). Calcium seems to have a lot to do with energy and the way it used, and what is Special Attack but a Pokemon directing a certain kind of energy?
Zinc: For Zinc it might be better to describe what happens if your body is lacking it: A lack of Zinc has been connected to many diseases, retardation, delayed sexual maturation, infection susceptibility, and diarrhea which all lead to eventual death. Zinc seems to have to do with activating the bodies various health maintenance function (and it's also the second most common metal in organisms, Iron is the first), which I would say fit with it being for Special Defense.
Carbos: Carbos is short for "Carbohydrate", carbohydrate is the body's essential source of energy. Without carbohydrates you're not going anywhere, which I think is appropriate for Speed.
BTW, I'm VERY generalizing what each of these chemicals do, they each do a ton of other stuff in the body which pretty much all translate to "you need it to live". I'm just picking out the functions they do that could be stretched to relate to the stats they're associated with.
I'll also go with a cop out answer of pointing out that a Pokemon's body is different from a human's body, so Pokemon can have these vitamins do whatever they want.