I'm pretty sure that was answered by now since im months late, but both lati's are available in the game. one roaming and one stationary.
and about the roamers, do you guys mean that a roamers stats are set so that everytime you encounter it, it's the exact same pokemon? or is there a set pool of stats chosen? because I've saved before capturing roamers, written the nature and stats, reset and did it again multiple times and never got the same pokemon. And also in Diamond, I was watching a friend play and he encountered shiny mesprit. It ran away. According to this, it would always be shiny wouldn't it? He found it again and it wasn't shiny.