My friend transferred a pet to me and I want to battle it, but it won't let me. Do you have to wait a certain amount of time before you can battle? If so, how long?

For transferred pets, you need to wait 30 days before you can battle with them.

Thanks but why so long???

It was a rule update the implemented maybe a couple of years ago. People were transferring high tiered pets to friends in order to win expensive loot from challengers that only show up once a year. Staff wanted to discourage people from transferring pets back and forth for the sole person of winning double the loot with one pet instead of using two pets.

Oh, that makes sense. Thanks

You're welcome! You can still train that pet in the meantime and buy weapons and such so you will be ready to take on opponents in 30 days :D

That's awesome! I got a really great pet from my friend, so now I can make it even MORE great while I wait 30 days! ?

Yes! You can train your pet in the training center: https://subeta.net/explore/train.php

You could also train with boosters, but that can get expensive really quickly. You can check out this link here for a bunch of useful guides and for the list of all boosters: https://subeta.net/forums.php/read/141562/Useful-Battle-Links

Once you are able to battle, your pet can win experience. You use that experience to buy stats for your pet and is the easiest way to gain stats. There is another guide here that will be very helpful to read:

https://subeta.net/games/battle/battleguide.php