Brawler said:
Toxitank is just a tech line, not really a deck. GG was arguably the best deck of all time, and I don't see how a failed states idea will beat it easily.
Careful there, buddy. You're calling the deck that got me fourth at Georgia States and second at Florida states a "failed deck idea", and personally, it makes me a tiny little bit mad. I don't play it now, but I was rather fond of it when I did play it.
Toxitank is NOW used as a tech line, but in the past it was a viable deck strategy. And when G and G comes around, Toxitank will one-hit KO your entire field. As for those other decks you mentioned, really, they're quite easy to counter. Toxitank is perfectly capable of becoming ToxiTECH, which is a teched it version. A line of Luxray, for example, would work great against Gatr.
My idea has its flaws, of course, but to call my deck a failure and yours the best deck of all time is just slightly arrogant of you. G and G was a good deck in the past, but it has little way of competing now, even with Double Colorless. We have Upper in this format. Sure, it's not nearly as good, but you can get up and running after they take a single prize, so you'll only have to make a minor comeback. One prize is easy to overcome, just look at stuff like Gyarados.
Edit: about my Luxray point, I just realized Gatr has a Grass weakness.

So disregard that point.