Just out of curiosity, if there is a large but discrete amount of crossovers in a given fusion/crossover, like say five different series, is it a megacrossover? How many series need to be included before it counts as a megacrossover?
If five is a megacrossover, what about four?
I think everyone can agree that a fusion or crossover blending three different series is still just a crossover and fusion, as I've seen plenty of Ranma+Sailor Moon+Other, or Buffy+Stargate+Other or Stargate+Harry Potter+Other or Charmed+Buffy+other. Those are just the five most common off the top of my head.