Monster Zero x SciFi Japan - Archive Only

Here's Toho Kingdom's page on it:

http://www.tohokingdom.com/cutting_room ... dzilla.htm

I guess Toho were in a real crossover kick once King Kong vs. Godzilla hit it big. First they considered following it up with a rematch, then they thought about pitting Godzilla against Frankenstein. Then they realized they could make some great crossovers using just their own characters, and the next four Godzilla movies all featured at least one monster that first appeared in a non-Godzilla movie, eventually culminating with Destroy All Monsters.