Just add -tard to the end of the name. If it's more than 2 syllables, cut off the rest of the syllables and add -tard to the end.
I'd have to disagree with that. Remember that "-tard" comes from retard, emphasizing that hardcore Naruto fans are idiots, (even though the term is, from what I've seen, embraced by Narutards, much like the general word "otaku" is). Putting -tard at the end of a show's name for its hardcore fans doesn't really work too well.
What xxxchihiroxxx did with Pokemon works well. Poketard sounds weird; Pokenerd sounds better. (I'm trying to think of one for Ranma 1/2 fans such as myself that doesn't sound stupid, but with no luck).