Now that pets are summoned through spells, we no longer have to worry about deciding which pets to carry with us on our exciting adventures. We can just bring them all! However, the problem of deciding which pet to summon at any given time still remains. Fortunately, there is a simple macro that was submitted by one of our members to randomly summon any pet from your entire collection:
/run CallCompanion("CRITTER", random(GetNumCompanions("CRITTER")))
In addition to this macro, there are plenty of wonderful addons available for pet collectors, all of which are working with the latest patch.