So, now that we've gotten a better look at Skar it appears just like Kong his design is based on several primates and might offer some insight to his full character and personality. In Kong's case, his design has features of both Eastern and Western gorillas, with human features added into the face and body posture. Both species are territorial but not exceptionally aggressive, usually they put on a threatening display and try to scare off intruders before actually throwing hands with them.

In Skar's case, an orangutan is the main design for the body, but obviously like Kong will be more humanoid with an upright posture. The face though has hardly any human features blended into it, and appears to be more heavily based on a chimpanzee than an orangutan. This would explain his personality quite a bit, as orangutans are normally one of the most peaceful and intelligent of the great apes, whereas chimpanzees, especially males, are know for going from calm to an absolutely explosive rage in a heartbeat and violently attacking with minimal provocation. Case in point, chimps are consistently on the instant kill list for zoos if they escape from their enclosure while the zoo is open. Lions, bears, tigers, gorillas are all on the tranqu and catch list, but chimps are on the shoot to kill on sight list.

Based on those features I'd say that Skar is going to be, in some ways, much smarter and devious than Kong and better at exploiting situations to his advantage, but prone to much more violent behavior.