I can't believe I have to do this, but here we are: time to explain why Scrappy Doo does not qualify as pure evil.
Who is the candidate?[]
Scrappy Doo is the infamously annoying and unpopular nephew of Scooby Doo who was later made main antagonist of the critically panned live-action film Scooby Doo: The Movie. Basically, he decides to take over the world with a demon army and kill the gang for kicking him out after he annoyed them once too often.
Why shouldn't he qualify?[]
Anyone who's seen the movie should back me up on this: he isn't presented seriously at all. In the flashback to him getting kicked out of the gang, he's played for laughs, being humorously dumped on the side of the road after urinating on Daphne. When he's initially revealed as the villain, it's pretty much just "hey, remember that tiny dog from the show that everyone hated? Well, he's the villain! Isn't that funny?". And after he's eventually defeated, he reverts back to just being the butt of painfully unfunny humour, with a "joke" about him knowing the word "b*tches" after he tries to insult the gang but gets cut off. Plus, after he transforms back into his normal self, (he had previously turned giant) they have a joke where, despite being tiny, he still attempts to defeat the much bigger Scooby Mano et Mano, and gets punched off-screen instantly. I could list more examples of him being more for laughs than anything else, but the bottom line is, he isn't serious enough to qualify.