On my hunter team some pets are on the left, some the right. Maybe it depends on the pet? In any case once you consider how big some are then add in followers theres no easy way to gather.

Since my team's attack macros call the pets if they dont exist, I just dismiss all my pets after combat when I am in the world, I have the habit to press that right before I mount every time. I wont bother gathering with my pets out.