You're thinking about stat pools incorrectly. It functions in a much more simplistic manner than IVs in Pokemon.
Each pet has a stat pool. The size of this pool is based on two characteristics: Pet level and pet rarity. All pets that share the same level and rarity share the same stat pool.
Its from this pool that a pet's abilities are derived. The stat pool may be allocatted differently among different pets: You may encounter pets that favor speed over health, or variants of that same type of pet with a more even distribution of thier stat pool, that favor no one stat above the other. But as long as the pets share the same level and rarity, there is no difference in the size of the pool their abilities are derived from. From the perspective you are considering, no pet is better than any other pet of the same rarity and level.

