If I had all the collector edition pets...
Starcraft Dream Team: Grunty, Zergling, Mini Thor
Diablo Dream Team: Mini Diablo, Mini Tyrael, Murkablo
If I was being silly....
Orphan Death Squad: Argent Squire, Curious Wolvar Pup, Curious Oracle Hatchling
Whats for Dinner: Elwynn Lamb, Plump Turkey, Little Fawn (alt: Crawdad, Crab)
Lovers Not Fighters: Peddlefeet, Stinker, Mojo
Inanimate Objects: Enchanted Broom, Enchanted Lamp, Alliance Balloon
If the pets are going to be merged for all toons... (cause my alt has a pet my main is missing)
Elemental Dream Team: Frigid Frostling, Pebble, Scorchling (alt: Kirin Tor Familiar)
But if I had to pick a balanced team... one beast, one mechanical, one magical
Dirty Dream Team: Gold Mini Jouster,De-Weaponised Mechanical Combanion (MechaRabbit), Dark Pheonix Hatchling
But like pokemon, I always picked the ones I liked... but ended up playing the ones that had the best tactical abilities.