You can read the announcement on the Japanese PokemonGOLive Website.
Tickets are free if you win.

#PokemonGOFest #PokemonGOFestYokohama #Yokohana #PikachuOutbreak

Current Raid Bosses - GO Fest Yokohama

Tier 2 has been restored to the original Rayquaza line up and a few GO Fest related Pokémon have been added to Tier 1.

Save a copy at leekduck.com/boss/

#PokemonGOFest #PokemonGOFestYokohama #Yokohana #Kirlia #ShinyPoliwag #CurrentRaidBosses #Rayquaza #ShinyRayquaza