Most often utilized PvE teams?

[Raftingshock]

Ikky, Lil' Bling, and Knockoff Blingtron are my go-to fighters for a variety of bouts.
Which teams are often used by others?

[Deborahward]

To me:
Undead: Unborn Val’kyr, Blighted Squirrel, and Infected Squirrel.
Critter: Rabbit, Snail, and Darkmoon Rabbit.
Magic: Enchanted Broom, Nexus Whelpling, and Arcane Eye.

[Gráinne]

Xu-Fu's https://www.wow-petguide.com/ is the place for teams for different battles, and it has a list of Most Used Pets https://www.wow-petguide.com/Guide/58/Most_Used_Pets but not Most Used Teams, which makes sense, since the value of some PvE teams is to level pets, and when you get to the more difficult battles, you will probably want to tailor your team to the battle.

I do keep some general teams of triples for quick wins on generic Family battles, like triple-Ikky, triple-Nexus.