Sorry, but you just can't compare weather teams to broken stuff like mega-kanga :v, most weather teams had a relatively high amount of mons that could counter them, on the other hand, there were very few mons that could beat and/or take hits from mega-kanga, you'd have to either focus on it by double targeting, rely on sitrus/intimidating/burning to take hits or rely on cheap strategies that require predicting such as switching out a mon into something with rocky helmet (garchomp, ferrothorn and amonguss were the most popular ones) and taking a fake out from it, making kanga lose half of its hp right away.
Also, in VGC'12 and '13 (years in which politoed and ninetales got their weather abilities) weather teams did get pretty popular at one point, however, people slowly stopped using them and started using 'mons like scrafty, landorus-t, liepard and breloom (i.e. in '13, since most of these weren't allowed/didn't have dw abilities back in '12).
TL;DR:
Previous years aside from gen 4 are nothing compared to this year in terms of diversity, especially in 2013, which was the most diverse year of all of them imo. VGC'14 was just extremely disappointing to me, but as I said, I have great hopes for ORAS and VGC'15 (: