Legendary pets start out as babies, grow into adolescents, then finally become adults. They grow up gradually, but the more attention you give them, the faster they grow. You can give them attention by:
Having your pet follow you.
Interacting with your pet, such as by asking them for one of their emotes, at least once every 30 minutes.
Pets gain Pet Points - the pet equivalent of XP - even when they are not being interacted with, including when you have logged out.
If you want to see your pet grow up faster, Solomon has a range of pet treats available to boost the progress of your active pet, or even to grow a pet into the next category immediately.
As they grow, pets learn new abilities and change in appearance. You can change your pet's appearance to a previous version if you prefer, but you cannot change to a stage that your pet has yet to reach (so you cannot choose the adult appearance if your pet has only grown to adolescence). Note this is just the physical appearance of your pet, it does not change the skills it has learnt.
The skypouncer has the following features:
3 appearances - Unlock new appearances as your pet grows, and choose which one to call.
Forage - Find useful items, like a Summoning familiar
Deposit - Periodically take an item to your bank
Scavenge - Bring you loot from a fallen foe
Lots of animations and behaviours - interact with your pet in different ways at each age, and watch it play with the environment and others of its kind