Because they swag 😎

Well, yes, but also another reason

I could low key imagine it being because e they have a large variety in personalities.. snorlax is lazy, raichu is jock, dragonite is the like… wise one. Popplio is the fun one, etc

Well actually, in the comic, Snorlax is actually more active that most of his species, Raichu is the leader, like Robin from Teen Titans, and you were right about Dragonair