Predator movies should be like the first 3, all stories in the same universe, but that aren't necessarily connected or dependent of one another.
The first 3 Predator movies all work even if you don't have watched the others, they are stories about a group of people with a common goal being hunted by something they don't know. The Predator broke this formula by making the Predator known to the main characters halfway through, it was also too silly, and that's not even getting on the multiple retcons it tried to make to the lore.