Pygmy Mountain Gorilla is a level 15 creature that is found on Secret Island. It is not especially difficult to tame. The point is that it spawns in a wave area, which makes things a bit more difficult. It is very important to stay just outside the wave area during the hunt in order to avoid Mountain Gorilla waves to start. The best position is [38184, 19467] and you need to be equipped with a long range weapon to be able to tag any spawning Gorilla. Then you have to kill regular Gorillas over and over again until a Pygmy appears. The regular Mountain Gorilla spawn is extremely small, with two Gorillas occuring at the same time at most. All you need then is patience...

The problem with the tamable papoo spawn south of Crystal Center seems to have been corrected. Yesterday I went to Next Island and found Adaptable Brown Papoos that can be tamed. These are level 1 creatures and are therefore very easy to tame. Once tamed, their name is changed and they are called Lofven Papoos. They cannot be exported to any other planet so you can only summon them on Next Island and Secret Island for the time being.

Edit: The issue is not solved. Most spawning papoos are immediately killed by the nearby turret. It is only in exceptional situations that some of them spawn outside of the turret range and can survive.