I've written (and vanished) fanfiction of many genre and anime/manga, and I do happen to have cliches. I'll begin with the DC ones.
1. Conan's thought process. While his dialogue is okay he will have internal conflict about being turned into a child and hiding and also a bit of dangerous kind of thrill when he uses his bow-tie to do someone's voice.
2. Insane stunts and detailed soccer movements xD (the only action ones I wrote were taken down a day or two later =3=)
3. The plot will end at a cliff hanger. LOL Not that I have written anything greater than 4 chapters lol
4. I shall be finding ways to incorporate the style of my favorite authors in my fanfics xD
5. If there is an OC, then for some damn reason you can expect their name to begin with a L or R. orz
6. Avoid lengthy paragraphs since it's pain to read them on the screen.
All I could think of.
Now regarding the ones stated above by ranand- oh sorry you get the idea of the name I'm a hardcore AiCon fan ^^
1. has too many mary sues but I have yet to find a gary stu (excluding meh) xD
2. Ran is to danger as salt is to food.
3. That's a fact of DC but he does have his cool moments
4. People are lazy.
5. She has no valid reason to so I guess they are anti-Haibara. :V I once read a fic in which Ran hated Ai. But it was logical since Shinichi was dating her. Love is the getaway key for female hatred in my writing. xD