I don't see how this is actually any different from what you are saying it is not. Essentially you are saying, a Pokemon that is competent does not require Substitute, but all competent Pokemon have it. Additionally, that logic seems like more of something for a study of Substitute, not sketch. We should not be looking at how Sub affects Sketch. It is about Sketch and only Sketch, so the argument that we should be looking at how Sub affects it is irrelevant. Wanting to know how Sketch affects Substitute is fine, but it is just one possible thing, and is not necessary at all.
We appear to be speaking at cross purposes then, or as it were. You are saying, I think (and by all means correct me if I am wrong), that we should not include Substitute because it has an effect on Sketch. I am saying that we should include Substitute precisely because it has an effect on Sketch. I am interested in what the result is, because it is less predictable. If we are concerned about generating what has been called "a successful CAP" in the past, which essentially only means that it fulfils the concept and nothing else, then yes, the alternative view of thinking may hold water.
More to the point, I fail to see how the concept concerns Sketch and only Sketch. If that were true, we would not have given the Pokemon any moves at all. Though I see what you are saying, in that Necturna ought to be forced into being balanced in order to best determine the answers to the questions the concept raises, I do wonder if that is actually what is most important at this stage. For me, in any case, I prefer to maximise exactly what we are now prepared to chance - there is no need to cut corners when we're on the straight and narrow.
And yet despite your analogy, you do not once dispute the fact that Wobbuffet is competently built. Sure, it might be sad and pathetic, but it is still competent. Now I know I probably could have come up with a better example than Wobbs (I just like him, so what?), but the fact is, no matter how strangely, Wobbuffet works and is a competent Pokemon. An important point is that people look at Pokemon like Wobbuffet and think, "well yeah, it is competent, but it is a gimmick. That is not how normal Pokemon are competent." Well, in case you have not realized, Necturna is a "gimmick" Pokemon too.
I guess I didn't make it clear enough then. Wobbuffet is not "competently built". Similarly, a hypothetical Pokemon with 200 base Speed, 200 base Attack, Scrappy and Tinted Lens as abilities, and Explosion as its only move is not competently built, regardless of how well it may or may not perform. Perhaps we simply differ on our definitions of "competently built". "Works well in OU" or "competitively effective" does not equate to "competently built". For the sake of argument, my working definition is something along the lines of "A Pokemon that is both competitively viable and stable without over-reliance on any single element of its construction". Hence, not polarised, as Wobbuffet is.
Also, Necturna is not, when you disregard Sketch, a "gimmick" Pokemon. At least, it shouldn't be. The big big point behind it was that it should be a competently built Pokemon in its own right. "Gimmick" and "competently built" are not mutually exclusive, regardless. When regarding elements of Necturna's design you have to be willing to temporarily ignore the presence of Sketch, as that's the variable we are supposed to be investigating. This starts to lose meaning when you start pre-empting what will happen assuming its presence to be a factor. I should clarify that this point is null when applied to measures of brokenness, where assumption of Sketch is integral. But this is not the point debated here.
But even so, with all the tools she is getting, Necturna is going to be competent no matter whether we give her Sub or not, even without Sketch. Great stats and typing along with what will be at least a decent movepool are more than enough to make a Pokemon competent. Now it might not be as competent as you would like, but that is a result of us not giving it any move it might want to Sketch, not because of Substitute. So as far as I am concerned, the correlation between Substitute and "competence" is completely irrelevant here, if it is even existent at all.
I will say it again: Substitute was, is, and remains a key strategy that every ordinary Pokemon can use, and by arbitrarily combing it we are removing a combination that would be available to any other competently built Pokemon, were said Pokemon given one use of Sketch. I am not sure where this "correlation between Substitute and competence" comes from, since as I have said before, Substitute has only the bearing of the average move on whether or not a particular Pokemon is competent, but is a natural variable that has to be taken into account in a test of this nature. In short, that we are skewing the results unacceptably by removing it.
I will say that this is very true, and we are definitely in agreement that we cannot say for certain if it will break it or not. So this should not be a point for or against Sub. If we have other reasons not to give Sub, then why risk it, but by itself I would not say that this is a reason to disallow it.
"Why risk it?" is an interesting question, but I believe strongly that CAP is designed for us to take chances in order to see what the effects are. We aren't learning all that much if we repeatedly play it safe.
I never said it is the ultimate move, simply that it might be. If you look at competitive Pokemon, what move is more prevalent that Substitute? Its power is undeniable. And I would certainly contest your assumption that it would never be Sketched. Do I know for sure? No, but I certainly think it is possible. And I think learning whether it will be or not is more valuable than seeing how good the predictable sets are with Sub allowed.
Substitute requires a prerequisite for effective use. Typically this is a strong natural attacking move combination or raw power, neither of which Necturna could be described to have in spades. There is a reason that Gyarados does not use Sub+3 attacks sets (it does use SubDD, of course, but that's because Dragon Dance is an incredibly good move). Substitute absolutely requires the backing of a large movepool, which is something that Necturna likely will not be able to provide.
As for your second point - I think learning how Sketch affects a Pokemon
Also, on a different note, it will never be Sub Seeding with Sacred Fire anyways, as, unless the OP has a mistake, Leech Seed was disallowed.
What I said was that it could not use Leech Seed and Sacred Fire on the same set. Not sure what the inconsistency is here.
I would start talking about the "fairly accurate predictions," but that is another topic completely. Basically, what I am trying to get at is that Substitute is a very powerful move, and, more than people give it credit for, it shapes the sets of all Pokemon. I simply think that we will actually see a greater variety of types of sets without Substitute than if we allow it. We know how Sub boosters and Sub + 3 attack Pokemon work. We should be looking at how Sketch makes a Pokemon work, not which coverage move fits best with Ghost and Grass on a Sub set.
There are few Pokemon, to my knowledge, where Substitute is the be-all and end-all of absolutely everything they do. Certainly there are Pokemon who are powerful users of this move, such as Hydreigon and Heatran, but this mainly stems from, not surprise factor, but fear factor - the biggest attributes for both of these Pokemon are their respective abilities to come in and threaten. Were Substitute sets the standard, or the only options, they would lose a large amount of their potential viability. Hence for them to be successful requires a climate in which other sets are not only viable, but popular. Necturna does not carry with it the immediate threat that Heatran and Hydreigon do with any of their sets - it is around the same in terms of bulk and Speed, but lacks their immense offensive potential and, more importantly, coverage.
As far as I can tell, with or without Substitute there will be exactly the same number of viable sets, but with one difference - With Substitute, sets that use Substitute will be viable. Without it, they will not. At least, that's what I feel relatively comfortable in predicting. The fun is in the finding out.
Unfortunately, I think this is the kind of argument where flavour starts to leak in. I don't want to accuse you of having a flavour-based argument, but really, what I get out of this is that you don't think it is distracting simply because everyone has it, and thus we are used to that type of strategy being on Pokemon. Simply put, the only reasons you present for it not being distracting are all based on the fact that all Pokemon get it. Whether or not it is based on the competitive fact that all Pokemon get it or the flavor reasons, that is simply not a convincing competitive argument to me. I think a good way to look at it is to think as if only 25% of Pokemon had it. If it was not such a universal move, would you still think that Necturna should get it? It should be about how it affects Necturna, not how it affects all the other guys who get it.
I am not sure whether you are intentionally strawmanning my argument but whatever. My argument for it not being distracting is because it is an inherent part of all competent offensively-built Pokemon, in the same way that having an ability is inherent, and because of this merits looking at less as a single move and more as a battle condition in and of itself. Suppose, for example, that Politoed were the most-used Pokemon in OU, and no other weather-changers existed. In this case, rain would be the default battle condition, and hence it would affect our Sketch options. Close Combat or Earthquake becomes more reasonable under the circumstances than Sacred Fire, say. This is an extreme example, but highlights the point - there should be a base element of doubt in all Pokemon, which is applied by Substitute, and Sketch manifests itself in the form of new doubts. Such is the basis of unpredictability.
As for your question of whether or not I would feel the same way if it were not a universal condition of the offensive Pokemon, then no, I would not. In the same way that I wanted Taunt and Encore and Acid Spray and every single other move that has been brought up in this thread disallowed. I am not entirely certain of the meaning of that final line of yours, so I cannot in good grace answer.
As far as I can tell, your argument for it being distracting is that it defines the sets that are most usable. This is the case for almost every other Pokemon in the game, and yet it does not seem to do so in that sense. True, they don't have limitless unpredictability, but on the other hand they have a far greater scope for use of Substitute. Substitute is an incredible utility move, but that's all it is.
As for the aspersions on my reasoning, I should merely like to state that it depends, I suppose, on your definition of flavour. As far as I can tell, the only reason that what I said could have been interpreted as flavour is if you count flavour as being "everything that does not pertain to whether or not a move will break x Pokemon", which is certainly not my definition. There are few other ways to argue the competitive case of a move that has no quantifiable impact. My argument is based primarily on what we can expect to get out of the project and what we will learn, which means that I have an interest in relating Necturna as closely as possible to pre-existing Pokemon for comparison. To remove Substitute, in my eyes, as I have said before, is to implement an exception rule that places Necturna on a different plane to all other offensive Pokemon, and hence removes the comparison aspect.
Perhaps the single thing we seem to be disagreeing on is our view of what the Pokemon without Sketch should be like. I say that it should mirror existing Pokemon as closely as possible, such that it is possible to directly compare them. You say that it should be balanced to the utmost possible degree, such that it is the making of the Pokemon and the learning process associated that is successful. Which is odd because, normally, I would agree with you.
I certainly see what you are saying here. However, I think this is the kind of situation where people give Substitute too much credit. We have already done multiple things that would never be done on a "normal" Pokemon, and yet it is not having Substitute that sticks in People minds as the one thing that it needs to have to be an accurate comparison. Honestly, it is different enough already that I don't see why this should be any more important than anything else.
I don't see it that way. There is little in the build or design of Necturna that is vastly different to most ingame Pokemon. Substitute is perhaps the only and, I think crucially, the most competitively relevant exception, which means that yes, it will affect our ability to compare and contrast, especially considering how common it is.
Why is how Sketch interacts with Sub any more important than how it interacts with any other move?
That is the question I want answered. If you can tell me that, then I would consider changing my mind. But right now I see negatives that outweigh the positives, so as a move I see as no more important than any other, that means I think it should not be allowed. It is as simple as that.
This question seems to be irrelevant. Sketch's relationship with Substitute is only important insofar as how Substitute relates to the functioning of any ordinary Pokemon. You may well say "a move no more important than any other", and I would tend to agree with you. But its importance has no bearing on the argument, only that it happens to be a natural doubt condition that is common to all offensive Pokemon, in the same way that Protect is (with the exception of stuff like Regigigas).
I certainly can't convince you to change your mind, because your argument is operating along a totally different plane to that of my own. This is, I am afraid, a difference of opinion, so all I can do is propose that we agree to disagree.
