My most favorite in-game team would have to be in my Pokémon Y version, which currently consists of Togekiss, Gyarados, Dusknoir, Machamp, Breloom, and Bronzong.
Dusknoir and Bronzong play defensively, and buy me time whenever I need some. Togekiss on there as I find it pretty easy to utilize, thanks to the combination of Serene Grace, Thunder Wave, and Air Slash. Machamp and Breloom--similar story. As for Gyarados, it's my physical sweeper. After one Dragon Dance move, it instantly becomes ready to take down any opposing Pokémon that gets in its way.
To be honest, I'm very satisfied with this set of crew. Been able to defeat a ton of my friends with it in the past!