>>6426I keep Latias in my party, and Meloetta, though I hardly use Meloetta in battle, she's more reserved for Amie and contests.
I also keep all legendaries out of my competitive battling, even the allowed legendaries like Latias; they feel cheap, and having Latias in my comp team also prevents me from using Gardevoir as my mega-evo. I did not take ages to breed me a shiny gardevoir with a perfect statline and nature to have latias steal her spotlight.
Did I use legendaries in my first walk through the Elite-4? Nope, though as a result the champ was quite a bitch to beat, in particular because of the primary typing of my team. (Gardevoir, Espeon, Metagross, Rhydon, Ninetales and Fearow.)