POKEMON GENDER VALUES EXPLANATION (GENERATION III)
Every Pokemon is assigned a number (one byte, ranging from 0 to 255) that controls their gender. This is regardless of their gender ratio, so all-female Pokemon (like Chansey) and even genderless Pokemon (like Starmie) are given this number.
For Pokemon whose gender can be either male or female, there is a value known as the gender breakpoint which is the borderline between the determination of male and female. This breakpoint value varies depending on the gender ratio of that Pokemon. This table shows the possible ratios and breakpoints:
| Male: 75%, Female: 25% | 64 |
| Male: 50%, Female: 50% | 128 |
| Male: 25%, Female: 75% | 192 |
| Male: 12.5%, Female: 87.5% | 224 | So in other words, if an Abra, whose gender ratio is 50% Male, 50% Female, has a gender value of 0 - 127, it will be female. If its gender value is 128 - 255, it will be male. The Psydex has a listing of the gender ratios for each Pokemon.
MIRAGE ISLAND
Mirage Island is a secret island that appears east of Pacifidlog Town, on Route 130. Mirage Island will only appear if you have a "Mirage Island Compatible Pokemon" in your party. On this island you can find wild Wynaut, as well as a Liechi Berry plant.
So what is a Mirage Island Compatible Pokemon? Two bytes control this characteristic. One is random and undeterminate at this stage, the other is the gender value. If the value of these two numbers is exactly equal to the "Mirage Island Number" for that day, Mirage Island appears. The range of two bytes is between 0 and 65535, giving you a 1/65536 chance of getting a Mirage Island Pokemon.
Fortunately for our sakes, there is a man in Pacifidlog Town (Check out the eastern-most house) who will tell you if he can see Mirage Island. Just talk to him, and if one of the Pokemon in your active party is "Mirage Island Compatible", he'll say so.
 
The Mirage Island Number will change each day, so a Pokemon may be Mirage Island Compatible today, but not tomorrow. Make the most of it while it lasts!
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