Here's some talk of a pretty crazy pet exploit being used in Arenas, and Blizzards plan to fix it.

Recently I fought an arena team which included a hunter pet named the same as the team's priest. As a result, every time I tried to target the priest via any method other than mousing directly over him (via proximo addon or /target command) I got the pet instead.

I was informed by a GM that this is legal. Is that correct?

If so, may I suggest that all /target functions prioritize targeting players instead of their pets? Or make it impossible for a pet to share the name of a character on the same server.