To trade a shiny Pokémon in Pokémon GO, the Stardust cost depends on your friendship level with the other player and whether the Pokémon is already registered in both players' Pokédexes. The costs are as follows:
- If the shiny Pokémon is registered in both Pokédexes:
- Good Friend: 20,000 Stardust
- Great Friend: 16,000 Stardust
- Ultra Friend: 1,600 Stardust
- Best Friend: 800 Stardust
- If the shiny Pokémon is NOT registered in both Pokédexes (new to one player):
- Good Friend: 1,000,000 Stardust
- Great Friend: 800,000 Stardust
- Ultra Friend: 80,000 Stardust
- Best Friend: 40,000 Stardust
Increasing your friendship level with the trading partner significantly lowers the Stardust cost. Trading shiny (and legendary) Pokémon is considered a special trade, which can only be done once per day per player unless an event allows multiple trades. Building Best Friend status over 90 days is highly beneficial to reduce costs drastically.
