Mexico City is 3 hours behind Brasília
Best overlap: 11:00 AM to 6:00 PM in Brasília is 8:00 AM to 3:00 PM in Mexico City.
The hours that work for both Brasília and Mexico City are 11:00 AM to 6:00 PM (Brasília) and 8:00 AM to 3:00 PM (Mexico City). 7 hours of shared hours is more than enough — slot meetings wherever they're most convenient for the people involved.