As an Isaac fan I remember being skeptical of the plant thing. The only reason I think I entertained it in the first place is because it came after the grinch hoax gained momentum. And I was also kind neatrual on the rathalos picture. The connections people made between it and GS WERE valid, that said, the concern was always if they were actually intentional, and if they were were they actually pointing towards playability? (the picture was in the AT section, so...)
And then there was the sun/moon theory that some Isaac and Skull Kids conjured up which was honestly probably one of the dumbest theories that popped up during Smash Ultimate speculation (and that's really saying something when chair theory exists).
Then there was the Japan earthquake, which I was also kinda not completely sold on when it came to smash speculation. I held the mindset that "this could point towards Isaac/Golden Sun, it could also point towards a bunch of other things since natural disasters are pretty common in entertainment media..."
Only thing that really got me in super hype mode was the Grinch hoax, and we all know how that went...