According to Bulbapedia
, a shiny Pokemon will have an Attack IV of 2, 3, 6, 7, 10, 11, 14 or 15 in Gen II (and the Defense, Speed, and Special IVs will all be 10).
Also in Gen II, a Pokemon's gender is determined by its Attack IV (0-15 in this generation) and gender ratio, with females having lower Attack IVs in species that can be either gender.
In a species with a gender ratio of 1/8 female & 7/8 male, the Pokemon will be female only if its Attack IV falls in the lowest 1/8 of the 0-15 range. So, the Pokemon's Attack IV must be 0 or 1.
Since neither 0 nor 1 are listed in the possible shiny Attack IVs above, female Pokemon from species with a 1/8 female gender ratio cannot be shiny in Gen II.