Spriting is an intricate art form that expands well beyond Pokemon itself, and as such, the answer to the question you're proposing would likely focus more on the techniques, skills and production involved in making sprite art as opposed to Pokemon. So no, it isn't allowed, because it isn't Pokemon-specific. I could ask a question about how to make or revamp Fire Emblem character sprites, and the answer to the question would be fundamentally the same as one asked with regards to Pokemon.
It would be like asking, "why isn't my 3DS reading Pokemon X"; this isn't a question about Pokemon, it's a question about a supposed defect in the 3DS console, just like how the question you've proposed is a question about how to design sprites and not exclusively a question about Pokemon.
We have to enforce this, because as soon as one thread is allowed that shifts its focus away from Pokemon, others will expect their own similar threads to be allowed as well. If that happens, we're either left with a difficult situation, or a Q&A full of questions with many different topics, each passing themselves off as a question about Pokemon.
