It's not an add-on per se, but you can do this at https://www.wow-petguide.com/index.php?m=Compare
I did not know this site. Thank you very much ^^
The first thing: I am Spanish, so I apologize if there is any inconsistency in the message, I am not good at writing in English.
Now, I would like to know if anyone knows of an addon that compares the pets that your character has with those of another player. And if there isn't, I leave it as a suggestion.
I have a lot of pets and I have guild mates and friends who also collect, however every time we want to compare we have to go one by one on the list and it is quite uncomfortable and tedious. And if we are more than two, even worse.
I would like an addon that, when selecting another player, automatically compares my pets with his, and tells us which I have that he does not have and vice versa.
I don't know if it can be done, but there I leave the idea.