I used to battle my friends with Blaziken, Rayquaza, Lugia, Ho-Oh, Gengar, and Alakazam, something like that. Of course, this was back in the days when Gengar's Ice Punch and Alakazam's Fire Punch (which took me freaking forever to dig up the BP for) were still Special. I had no concept of tiers, but I wrecked, even when my friends used teams that would be considered similarly tiered.
I've battled online a bit this gen, the first in which I've done so, with Chesnaught, Heliolisk, Gengar, Hawlucha, Blastoise, and Ledian/Butterfree. I do pretty well.