How to Get 100% IV Pokémon in Pokémon GO

A 100% IV Pokémon means all stats (Attack, Defense, HP) are maxed out at 15. The chance of catching one in the wild is about 1/4096. However, it's different when it comes to Pokémon caught from Team GO Rocket. This is because Shadow Pokémon get a +2 boost to each stat when purified. So, for example, purifying a Shadow Pokémon with 13/13/13 IVs will result in a 15/15/15 (100% IV) Pokémon. These are called 'Purified Perfects'. Furthermore, if you purify a Shiny Pokémon with 13/13/13 IVs, it becomes a Shiny Perfect Pokémon. So, if the Shadow Pokémon is Shiny, you can also get a Shiny Perfect Pokémon.