To what extent does Cute Charm affect the shiny chance, and in what games?

Question

In gen 4 (or at least HGSS), if the user's hidden ID was a specific value, it would trigger a rare glitch that would cause the shiny chance to increase to about 20% if a Pokemon with Cute Charm lead the party.

My question is, if the user's hidden ID is a value in which this glitch does not activate, would leading the party with a Cute Charmer make it impossible to encounter a shiny, at least in HGSS?
And what about games that came later? I'm shinyhunting using Cute Charm in White, and I want to know whether this is affecting my chances.

Answer 1

In Generation IV only, when Cute Charm forces a Pokémon to be a specific gender, it does so by setting its personality value to one out of 25 possible values that correspond to the forced gender (one value per nature). The set of possible values depends on the gender of the Pokémon with Cute Charm, and if the Pokémon with Cute Charm is female, the wild Pokémon's gender ratio. This has significant consequences for properties determined by personality value.
As a result, when the encountered species can be affected by Cute Charm (i.e., when it is not a male-only, female-only, or genderless species), the chances of encountering a Shiny Pokémon differ from the usual 1/8182, depending on how many of the 25 possible values forced by Cute Charm result in a Shiny Pokémon (in conjunction with the Trainer ID number and Secret ID): they may be as low as 1/24546 (if none of the 25 values forced by Cute Charm result in Shiny Pokémon, so the Pokémon can only be Shiny if Cute Charm fails), or as high as 21.34% (if 8 out of the 25 values forced by Cute Charm result in Shiny Pokémon).

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