Uhm... try this. For a legal PID.
Make Mewtwo's IVs first.
Then go to PID/IV.
Click Generate.
It should come up with a list of possible PIDs. Make sure it's Type 1 for Mewtwo.
You can have 510 EVs at max.
And... for ribbons, you shouldn't have (For Poke originally from Sinnoh):
Blue, Green, Red, Legend, History, Record, World, Earth, Sky, Land, Marine, Artist, National, Country, Classic, Carnival, Festival, Premier... er, I think that's all of them.
But ribbons shouldn't matter, as I have a hacked Flygon with all ribbons that passed PBR's check.
You can have Fateful on, too. I made a fan-made event that passed PBR's check.
And I don't know about the Max for Contest Stats, but I just know, it can't be maxed in everything.
Heh... did... that help?