This is how i wish poke'mon breeding worked: all poke'mon would have alleles for shiny or normal (normal being dominant of course) ********** normal (dominant) would be SS and heterozygous would be Ss. shiny (recesive) would be ********** ss.
you could breed two poke'mon with Ss alleles to have a 50 percent chance toward a shiny, (this is very Op though)
breeding two poke'mon with ss alleles would have a 100 percent chance toward a shiny, and so on (as depicted by the punnet squares and list).