honestly? just add Bad Apples to "Youtube Villains" - no need for creepypasta tag or MLP tag either.. as for the rest.. well Sparkles is also better as just "Youtube Villains".
Being on creepypasta wiki is NOT the end all of what a creepypasta is.. however dark fiction would be better just listed as "Horror" and "Youtube".
If they have videos on Youtube this wiki allows them, how else do you explain things like Stupid Mario Bros and Youtube Poop videos cropping up here?
tumblr however should not count - they can be removed rather quickly as they aren't really a valid medium (like Youtube)