While not all professions in GW2 have built-in "pet" skills, any profession can use summons that are triggered by equipment. What differentiates these summons aside from visual appearance? E.g., do some of them grant boons or conditions? Do they have notably different DPS or health? Or are they all essentially Generic Summon A, Generic Summon B, etc.?
I believe most or all such summons are triggered by Runes and Sigils. (Rock Dog, Parrot, Fleshreaver, Attack Bird, etc)
If we are talking only about the summoned creatures from sigils and runes, the best is to look directly to their wiki page. You won't get their complete builds but at least have an idea of the main abilities they have.
Some examples:
Regarding their stats, I imagine they are following some kind of template from the class they are based on (Thief for Tropical bird, Necro for Jagged horror, ...) and are level-scaled based on your own level (this is pure guessing here, no sources to give on this point)
Also, I haven't checked all of them but keep in mind that some of these Sigils/Runes may have changed since the April features pack update. However I doubt they would remove that summoning feature, but maybe some new ones may have appeared :)
