There's a rumor, which has been around for as long as Pokemon GSC has been around, that in said games, a Shuckle holding a Berry Juice will eventually turn it into a Rare Candy. I've not been able to find any reputable source on this (and no, people on forums saying "trust me it works i tried it" don't count as reputable), so I'm curious whether it's actually true.
I do see that one thing people seem to agree on is that it doesn't work in any games other than GSC. This suggests an easy way to unambiguously verify it: look in the disassembly and find the code responsible. But I'm not sure where to even begin, so if anyone here could find that or just give some guidance as to where to look, or give any other convincing argument (video evidence, perhaps?) one way or the other, that would be appreciated.