It's not shown, but it would make sense that some Great Valley dinos would be an patrol looking for sharpteeth getting into or near one of the main entrances. Though like the animators dislike animating things not dealing with the primary plot we're likely to not see this. As well as some ground dinos doing this it would be a good an easy thing for flyers to do since they can see much more of an area while flying then those who can't fly are. Though some of the larger and more brave ones would likely be near the entrances also in case any sharpteeth are seen they would be nearby. Which could be one of the reasons Ducky's father is so seldom seen, he may be one of those who spends time near the main entrances ready to fight sharpteeth, as well as maybe explaining why Threehorn is not seen in the 4th movie. Maybe he was busy offscreen for part of that moviie.
As for migrating we've seen many times when herds pass through and stay with in the great valley for a while before moving on. Ali's herd, Tippy's herd, also the herd the rainbowfaces were with in the 7th movie. Likely the herd that Tria was with, since I doubt she was walking around all by her self as she traveled to the great valley, though it's not stated. Bron's herd may visit it, though we've seen only him and Shorty, no mention of his herd. There have also been shown at times various longnecks and other individuals, some who may travel in small herds, or alone like Doc did, at least till he met Dara.