Allos stay alone until another allo gets close enough. When an allo finds another allo they will join forces and form a pack. The highest level allo becomes the leader once the pack reaches a size of 3 allos. A pack of allos will always follow each others no matter what. They usually follow the leader, but can follow a different allo if say a player calls over that specific allo to follow him . If they wander too far from each other the bond will be broken and the allos will set off on their own until they find each other again or other allos. Once a pack reaches a certain size the allos will stop accepting other allos in their pack. The same goes for tamed allos. Once they reach the max pack size of 15 and more allos are introduced your original 15 allos and the new allos will form different packs. Hope this helps you understand allosaurus pack behaviors. Thanks for reading.
Allos are my one of my favourite if not my most favourite creature in all of Ark and if I’m being honest I believe Allos are underrated, and I’ll tell you why. Some people question their uses because if you want a fast ground mount people tend to choose a Carno and if they want a power mount they choose a Rex or a Spino. Allos are in between, fast and a good damage; alone they are dangerous but in packs they are a force to be reckoned with because we all (or most of us at least) know about the pack ability that these gain when in a pack of at least 3, the bleed effect attack, now this attack drains 5% of the targets damage over 10 seconds which means using that specific attack, it can 20 shot any enemy. Using an Allosauruses bleed against a Giga or a Titan will significantly damage it but it would be best to use the Allos as the main damage while another dino tanks all the damage. Anyways, to further explain the pack bonus, the leader will be the highest level (obviously) and the leader does not only gain new attacks but they receive a 50% damage increase and a 25% damage reduction, so if you have an imprinted pack leader, it gains a total of 55% damage reduction which is an extreme damage reduction. There can also be multiple pack leaders, especially when in multiples of 3. Thanks for reading, I hope you found this helpful and might reconsider your thoughts on the Allos.