From Bulbapedia (
http://bulbapedia.bulbagarden.net/wiki/Shiny_Pokémon#Generation_V):
The secret ID and Trainer ID bytewords are first xored together, and then the first byteword of the personality value is xored with the second byteword of the personality value. If the xor of these two results is less than eight, then the Pokémon is Shiny. This results in a probability of 8 in 65536; simplified as 1/8192 (2-13, or approximately 0.012207%), just as in Generation II
So, it's a matter of probability, which is, very low (1/8192)
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~Theres a feeling deep inside me, and it's always there to guide me.
It's in my heart and in my soul, leading me to the ultimate goal!
You can try your best this might be fun
You go down to defeat before you begun!