The Summer 15 Shiny Rayquaza that was distributed in Singapore from May 5th, 2015 until July 31st, 2015 via serial codes has been banned from official Video Game tournaments and events. The official Japanese Pokémon Global Link website made the announcement on January 21st, 2016 but it had previously been noticed that it couldn't be traded over the Internet. The single quote in the OT before 15 triggers the hack check system. The ban does not affect other distributed event Rayquaza's from participating in official events though. Despite being distributed in Singapore, Japanese or North American region copies of X, Y, Omega Ruby or Alpha Sapphire could obtain it. Further details on this Shiny Rayquaza are available in our Event Pokémon Database.


Source: http://3ds.pokemon-gl.com/information/42dcc13e-bea9-4c67-9956-7f677bf2e488