At first these guys are passive and tame and can be given any type of berry. (Mejoberry is recommended) do not run up to its face. It will run away and it will keep running.(other monkeys near it will also run away too) simply crouch and feed it berries. Once tamed, they will love you forever.(they are a shoulder mount so put them on your shoulder and take them EVERYWHERE) they have a really cool ability to through poop at the enemy that is chasing or if it is your target. When it through the poop if it lands it will disable there ability to sprint for a little while.( and will take small amounts of dmg too while the poop is on them). I hope you found this guide helpful.
Ok to find it just look in the southeast part of the map (I play mobile so that map) then once you find one just crouch step behind it feed it then step back you need about 100 berries (preferably mejoberries) and once you’ve tamed it you can tame another then breed them but fail to feed the child via lack of kibble then breed them again and get a child then start super mutating them into giant mega beasts and reek havoc with a level 6000 mega monke and rule ark just to have it die to 3 gigas all attacking you while foraging for berries (somewhat based off of a true story)
Always stay crouched while taming. And never get close enough to touch it. While following the monkey, if the monkey ever stops, its very likely It will turn and start to walk in a different direction. So be aware that it might walk in your direction. Hope this helps : )