One possible theme is family. The puppy is part of a family or a group, and the stories could explore how it interacts with its family members. Maybe it gets into trouble and has to rely on its family for help, or it might learn from its family how to be a better puppy in different situations.
The main character is the poky little puppy. But there could be a mother or father figure for the puppy in the story. And perhaps there are some friendly animal neighbors. For instance, a wise old owl that gives advice to the puppy from time to time, or a frisky squirrel that the puppy tries to catch but can't because it's too poky.
The main character is of course the poky little puppy. It's the one whose adventures the story is centered around.
The moral could be about the consequences of being disobedient. The poky little puppy often strayed from its siblings and got into trouble. It shows that not following the rules or staying with the group can lead to difficult situations.
The main character is of course the poky little puppy. There may also be other puppies around it, perhaps its siblings or playmates.
The 'poky little puppy' is often about a puppy who is a bit slow or poky. It gets into little adventures, like exploring areas it shouldn't or getting left behind while the others move on. It's a simple and cute story for children.
I'm not sure exactly as I haven't read it in detail. But generally, it might be about the adventures or daily life of a polky little puppy.
Friendship is likely a theme, as it is in the main My Little Pony series. Maybe the pony puppy has to make friends with other ponies or creatures in the 'other stories'.
The little puppy is the central character in the story. But think about it, if it's a story about the puppy growing up in a farm, then the farmer who takes care of it, the cows and sheep it shares the space with, they all can be main characters too. In some cases, even an imaginary friend that the puppy has in its mind could be a character in the story.
Obviously, the little black puppy is a central character. But there could be other characters such as a wise old owl that gives advice to the puppy, a playful rabbit that the puppy chases around, and a mother cat with her kittens that the puppy befriends. All these animals play different roles in the stories, adding more colors and fun to the plot.
Love and friendship are common themes. Just like in any relationship story, in gay puppy stories, the relationship between the two main characters is central. And the puppy often acts as a catalyst for that relationship.