Shiny Giratina Altered has been available since September 2019. Every encounter with it has a 1-in-20 or 5% chance of being shiny — unless specified otherwise. Moreover, shiny legendaries are ...
The Shiny rate for Legendary Pokémon is approximately one in 20. When looking for a Pokémon with the best stats, the 100% IV Altered Forme Giratina will have a CP of 1931 in normal weather ...