Attention, Trainers! #PokemonUNITE will be in maintenance on September 21 from 2:00PM to 12:00AM PT. During this time, the game will not be playable while we make adjustments and prepare for the mobile launch. We appreciate your patience and understanding! Meanwhile, new cowboy-themed Holowear for Garchomp will be coming to Pokémon UNITE on September 22.
Source: Official Pokémon UNITE website