Here it is ^^^... I actually got some one from /r/translator who knows Chinese to translate it so we can get a better idea of what it said. We can now clear up 2 misconceptions.
> 1: That it only mentions that there will be a Fire/Poison Pokemon. According to this translation it actually says Fire/Poison Lizard.
> 2: That it said "No Gym Info". It said there would be No Gyms but also mentions what would replace them

So why should we believe this leak? Especially since Cresselia on Smogon refused to show a timestamp? Well there are a few reasons I mark out below
> They have been a member for 10 years. 10 years is a long time so they are not some new user trying to make something up
> Smogon approved their post. That's got to account for something
> The Chinese isn't inconsistent. Usually to determine whether a leak is real or not people check the spelling and formatting and no one found any flaw in this.