here are a couple of rumors that appeared in italian magazines of the 90's (of course these were probably published first in japanese and english magazines, but that's what i have)
It's a rumor about an isometric zelda for snes using the same ACM technology of DKC. Who writes isn't sure if it is an original title or a remake of the first zelda games like Mario all stars.
This is the most interesting of all, even if it's almost surely fake. As a boy back in 1996 i was so excited about this.
in this interview a guy from nintendo says that they are working on two sequels of earthbound (mother) and "super wario land" (a wario game for snes?)
not really a rumor, but this is the infamous "confirmation" of virtua fighter 3 for saturn and its expansion cartdge that would cost andy mee his job
Actraiser 3 for saturn :( poor quintet...
in another very infamous rumor miyamoto talks about a more "adult" character design for mario and luigi for the next mario game planned for dolphin. Yeah, that was probably about as true as the underground dungeons in Zelda URA.
does someone knows if any of them were true and the games were actually in development at some point ?