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.
No, but Shuckle can turn a Berry into Berry Juice
A disassembly of Pokémon Crystal is available on GitHub, and nowhere in it is code for having Shuckle turning Berry Juice into a Rare Candy.
However, this rumor probably has its origin in the fact that Shuckle can turn a Berry into Berry Juice after the player has visited Goldenrod City. This section of code includes a function that runs after the player has visited Goldenrod City, then has a 1/16 chance of a Shuckle holding a Berry turning that into Berry Juice.
ConvertBerriesToBerryJuice: ; If we haven't been to Goldenrod City at least once, ; prevent Shuckle from turning held Berry into Berry Juice. ld hl, wStatusFlags2 bit STATUSFLAGS2_REACHED_GOLDENROD_F, [hl] ret z call Random cp 6 percent + 1 ; 1/16 chance ret nc ld hl, wPartyMons ld a, [wPartyCount] .partyMonLoop push af push hl ld a, [hl] cp SHUCKLE jr nz, .loopMon ld bc, MON_ITEM add hl, bc ld a, [hl] cp BERRY jr z, .convertToJuice .loopMon pop hl ld bc, PARTYMON_STRUCT_LENGTH add hl, bc pop af dec a jr nz, .partyMonLoop ret .convertToJuice ld a, BERRY_JUICE ld [hl], a pop hl pop af ret