My favourite team? hmmm, i don't have a favourite team as such, i like quite a few. my teams consist of strategies i like to go for, i love playing with under powered teams and thrashing teams of legendaries.
The other day some guy challenged me on 3ds to a battle with no level cap so as you can imagine he had a full team of legendaries (mega rayquaza, primal groudon, primal kyogre, Mewtwo Gallade and Dialga). All level 100, my team consisted of a level 34 Jirachi, Lv97 Muk, Lv 62 Drifblim, Lv82 Liepard, lv 74 Golem and a level 68 Serperior.
I knew in that battle i'd have little hope of winning as my team where under leveled (and i had a damn level 34 in there vs level 100's) so as you can imagine my entire team got K.O'ed untill i was down to just my Muk and Jirachi. My Muk has a really annoyingly cool set which basically creamed his entire team (even though most of his team had super effective moves on me) my Muk killed his ENTIRE team. The annoying thing was the guy got salty and disconnected just after the battle so i couldn't save the battle replay! but it was hillarious as he battled me just before that match and he had put restrictions on (so all pokemon where level 50) where i used two pokemon to ruin his day in the first round.
For me i quite like using Stunfisk, Cloyster, Absol, Torkoal, Coffagrigus and Lilligant some teams as they are some of my favourites. I've just found a cool new strategy with my Hitmonlee which i love too, so it'll be fun battling with that :)