BakaNeko said:
Is this thread going to be official? I know that I've started to point people here for this.
I'd also like to add "Rampant crossover madness" as a faux pas.
Not all crossovers are going to work. In fact, unless you're a reasonable writer, many crossovers are not going to work.
Magic and technology tend not to mix - though there are exceptions (Outlaw Star, but that's because it's in universe). Also, different magics have different rules.
For example the magic in Negima and Bastard!! have differing principles.
Also, different technologies are not always compatible. Star Trek and Tenchi operate different technology bases, as do the Gundam universes and Babylon 5.
And finally geography does not a crossover plot device make. Yes, Juuban is near to Nerima, but then again, New Jersey neighbours New York - so does that mean I can have a Friends/Sopranos crossover?