Pokelogic

no no no, thats friezas worldbreaker

"Don't question it. I'm Mewtwo, bitch."

I used to have a crush on MewTwo

Pokemon Gold and Silver's first announcement to the Japaneese audience was in 1997 (although it was named Pokemon 2 at that time. The beta pictures showed Ecrutreak Town for example), and the movie was released in 1998. This of course means that Gold and Silver was in development before the movie was made, and the move would likely have been made before the work on the movie had begun.

Donphan was also in the movie. Blastoise used Rapid Spin and Donphan used Rollout, neither of those moves were in Gen 1 either. They obviously planned ahead.
Either that or Mewtwo was a fucking hipster.

"I'm fabulous."

I've had shadow balls before it was a move.

<=== "bitch please"

Because Mewtwo is much like the Honey Badger. He just don't give a fuck

It looks like some kind of dark kamehameha

perhaps they made him do the move shadow ball for commercial of the second gen that it's going to be made and that shadow ball will be included?

Same movie had donphan before it was a pokemon

MEW(FUCKING)TWO

What the hell was this?
I haven't watched the show since Master Quest