* Rayquaza is not a Pokémon that is available through Mystery Gift in Pokémon Black. Rayquaza is a legendary Pokémon that is only obtainable through specific events or trades.
* Shiny Rayquaza was not distributed as a Mystery Gift in Pokémon Black. While shiny Pokémon have been distributed in previous games as Mystery Gifts, Rayquaza was not one of them.
How to get Rayquaza in Pokémon Black:
1. Obtain the National Dex: You need to complete the game and get the National Pokédex.
2. Catch Rayquaza: After obtaining the National Dex, Rayquaza can be found at the top of the Sky Pillar, which is located on Route 134.
Note: You cannot find a shiny Rayquaza in Pokémon Black through standard gameplay, only through trading with someone who has one.