In regards to Fairy-type's supposed weaknesses and resistances, when Pokémon Smash did their skit last night, did things match up with what WPM's "source" claims it to be? Personally, I find the Fairy-type's supposed type effectiveness to be too good to be true. Giving Poison and Steel the physical punch they deserve, being immune to dragon and super effective against Dragon and Fighting (and Dark, but who cares about Dark?) is too good to be true as it pretty much fixes all of the problems with the type chart all by itself.
In regards to the name Patrice, I've been digging around for the name origin and so far I've been able to dig up:
Patrice -> Variant of Patricia -> Feminine form of Patricius (Patrick) -> Patrick derived from the Latin "Patricius" meaning "Nobleman". Most commonly known as being the name of St. Patrick, Ireland's patron saint.
I haven't found anything that links the name to any kind of tree or plant (but if anyone can find a link, then please correct me on this).
In regards to the Grass/Fighting, Fire/Psychic, Water/Dark rumoured type circle, in all honestly, it wouldn't surprise me. It could easily be GameFreak taking note of fans wanting a Fighting-Psychic-Dark triangle, but misinterpreting it and making it go the other way (when in fact a lot of people would probably prefer it to be Grass/Dark -> Fire/Psychic -> Water/Fighting to create a reverse triangle, like Gen IV's starters).
Then there's the issue of Mewtwo's forme. Other users here have quite rightly pointed out that if Mewtwo was receiving two formes, wouldn't they be featured in the movie together, or even revealed together? It doesn't add up.
At the moment, I'm calling it fake. Hell, I managed to get a fake rumour I made published on some Zelda fansites and it included things like the story for the next Zelda game being inspired by 50 Shades of Grey (Seriously 9.9). For the moment, I'd say to wait until something more substantial than a single attack comes out to confirm or contradict it.