Ok so Ive seen the new Pokemon movie with the "female" Mewtwo...dubbed, not subbed. I found a few things I could use from the movie to make Mewfii more legit...

First off, this Mewtwo IS female, not any of the old ones, the "male" ones...

Mewfii got her hair from an after effect from using Mewtwoite Y...

Mewfii did not have water power until the "female" Mewtwo from this new movie did that "I must pass my limit" thingy...she got a few things during that whole go into space and then fall back thing...When she broke into space she was gathering space particles and since going into Mega Y mode to control time/speed that was all was needed to create a parallel paradox, then the added that they were speeding back to earth that created a small rip inside Mewtwo when she was unconscious, and then when the Pokemon below them made that huge water ball, that's where the rip got caught and became the Birth of Mewfii...

Now if you want to get e into this, as a trainer, well I always follow Ash but never meet him, if he meets me, time will rip...

Now I always like to be and ex-employee of some big evil guy team, because either I'm just like N or like him...basically...

I do have a ability to transform into a Pokemon, essentially, I eat a ditto...heh, then turn into any Pokemon I see...see all in the name of stealth, I can communicate with Pokemon too, but just the ditto half of me...

So one day, I visit Pokemon Hill and choose a water Pokemon to change to and start swimming around, then I get to that bridge that Mewtwo and Genesect fell close to and find a little rip in space and time...why is the water not leaking out? Because in the rip there is water...why is the water not changing? The paradox is a gate not a leak, so normal water is not effected, but if something solid was to touch it, it would travel to the other side but would immediately come back...

When I'm swimming around in my ditto form, I hit the rip, pass through but pass right back, except I have baggage, that's Mewfii's DNA...now because of the shock, my form takes on Mewfii's form and things get hairy as my mind battles with her mind...

Now at this point I'm able to either be her or cast the ditto out and the ditto is her...She is not complete, kinda like in Kingdom Hearts, you have your main person, if turned into a heartless but had a strong will, that will produce a nobody...

So then I'm off on a journey to do a few things, get more Mew or Mewtwo DNA from ruins in Kanto, follow either Mewtwo, Old Maletwo or New Femtwo, will take a lot because they will be able to sense me in either me or Dittotwo mode, if they leave because of that I can still try and get the DNA from where they were standing...

So where does all the sexuality come into play? Well lets say this version of me is a little bit of a pervert at one place in my/his life and I shoved the perverted side to a shady part of my mind...

I think the best way to put it is I had a mate, while Mewfii was getting her own Mewtwo body, she must have sensed me and my mate...going at it, that's why she hates me for the first part of her life, but then finds out that that same mate went MIA, to Mewfii at least, and then she finds out that shes part of the New Mewtwo, a ditto, and part of my mate...she has three different life times...her actual name would have been Mewthree, but thats taken, but Mewfii would be easier to keep...it's like when in DBZ, Piccolo and Nail Namek fused and people didn't know what to call him and Piccolo was all like, "Piccolo: just call me Piccolo"

Now the ditto became Mewlii, when infused with grass/plant element...

As for Nateo, that was when nothing was inside of me...but is a byproduct of fusing with either Mew forms...when my rage boils I gain the fire element and turn into the flaming Mewtwo...