You can now invite Brendan to the Trainer Lodge and get Brendan & Swellow as a new sync pair in Pokémon Masters EX, you can invite Brendan once you have teamed up with Brendan & Treecko

DeNA is continuing to add more events and new features to Pokémon Masters EX on a regular basis. Read on below to learn more: Updates to the Trainer LodgeUpdates to the Trainer Lodge The following updates were made to the Trainer Lodge. Update Details Important We hope you continue to enjoy Pokémon Masters EX. Source: Official Pokémon Masters EX site