In terms of the type chart, I don't think they'd suddenly decide to make one type super-effective against another (although if the focus of the generation is types like the mosaic plaza could suggest, then they may see this as an opportunity to rework the type chart slightly).
In any case, one thing I could see happening is buffing weak types like Bug and Ice through non-type chart means, similar to how they made Dark immune to Prankster in Sun/Moon.
About the supposed leak, I haven't read it fully, but 130-150 new pokemon seems far too unrealistic; since the shift to 3D in Gen VI, we've been getting less new Pokemon than when the series utilised sprites, which is understandable since a lot more work goes into developing for 3D than 2D.
I predict a count similar to Sw/Sh; 80-90 new Pokemon, and 15-20 regional variants.
I have a hunch that Fuecoco won't be Fire/Ghost since, as we know that Hisuian Zorua/Zoroark is confirmed, it would not be a stretch to say that all Hisuian forms will carry over to S/V, so I imagine they won't want a crossover of types between Typhlosion and w/e Fuecoco will evolve into.
Water/Fighting for Quaxly, however, wouldn't be too bad; it's a combo that's only been done 3 times prior, and two of those instances were legendaries.