Gundam does not have one universal watch order: start with the setting
Universal Century and Ad Stella are distinct settings with different calendars.
Gundam includes series set in different worlds; its titles do not all form one continuous story. A useful first step is to choose a series that interests you and identify its setting.
Gundam Unicorn uses the Universal Century calendar and takes place in U.C. 0096. The number is an in-story year, not a claim that the anime has 96 seasons.
The Witch from Mercury uses another calendar: its official story page places Suletta Mercury in Ad Stella 122 as she arrives at Asticassia. To meet her story, viewers can start with that series’ prologue and episodes without first watching all of Universal Century.
A series’ internal order and its availability in Brazil are separate questions. Check the platform, region and language before watching.
