Pokemon is an odd series, isn't it? For every cute, wholesome element the series has, there's an equally ominous one brewing under the surface. Despite their poor attempts at retconning this in recent years, you can't undo the proverbial A-bomb that was Lavender Town! Is it the worst offense ever in a children's game? No. Have there been darker elements in the Pokemon game sense, especially when concerning the Pokedex descriptions of Ghost-Pokemon? Absolutely, but nothing hit quite as hard as that first real dose of mortality in our innocent adventure of forcing magical creatures into blood sports... okay, maybe Pokemon isn't that innocent after all!
All jokes aside, I'll actually admit that I don't have an issue or long standing trauma from Lavender Town or the Pokemon Tower. In fact, I personally like it's inclusion. It's that little dose of darkness that gives Pokemon it's whimsy and truthfully, I think it's what kept Pokemon from falling into obscurity. As adults, we often look back with retrospect now that our minds can comprehend existentialism and go "Wow, that was dark! Why would they show that to kids?" but as kids, most of us just thought "Haha silly ghost creature go boo!" Did it really scare us as kids? Probably not all of us and those who it did, I can almost guarantee you enjoyed that aspect... for the most part.
It's fun to be scared within reason, especially as a kid, that's why Halloween is so fun! I think it's Pokemon's ability to juggle light and dark elements, it's duality of both fun and scary that unintentionally make it really befitting for this holiday. Which explains why I've had not only three Pokemon entries so far, but an entire Pokemon devoted countdown in the past! Have there been other Pokemon that would be more fitting, like Gourgeist? Sure, but that initial does of fear that the original ghostly trio brought to the series is something that all other Ghost-types afterwards lend themselves to and for that alone I feel they're the most deserving of a spot. (Well that and because this entire countdown is about previous winner/runner-ups and there were the ones I drew within that criteria so...)