Black Kyurem can be shiny in Pokemon GO upon release. Going by how Fusion works in the case of Dawn Wings and Dusk Mane Necrozma, your Black Kyurem in Pokemon GO will be shiny if you fuse Zekrom ...

Don’t forget the shiny forms. When the time comes ... Hey don’t put it straight into that PC! Leafeon is another strong evolution. Leaf ears and a matching tail, yet it still looks fluffy!