I finished the Pokedex! Yay!!
As for sunrise/sunset, for some reason, in my game, the sun sets during 10-11 p.m. I'm in Central Standard Time. If it happens simultaneously globally, that would be between 1-2 a.m. in Buenos Aires... But if you have Moon (I do too but used Lunala to change the sunrise/sunsets), I'd guess it sets around 2 p.m.? At the equator, the sun usually rises between 5-6:45 a.m. and sets between 5-6:45 p.m. I'm not sure where they're basing this off of, unless it's utc??
Edit: And this is me with the wrong time set in my 3DS. Whoops!!!!! It definitely made the game easier to have the time change before bed, though!