Mewtwo. He's such a badass, especially mine in my silver game, just looking at that bastard gives you a stroke. I mean in the first movie he awakens in the laboratory he was born in and kills all of the scientists what made him. Then after he gets that armour from Giavonni (the Don of Team Rocket) he freaking kills him (Yes in the 1st movie Giavonni dies) and just look at him, he's just an evil demonic being.

Alakazam is cool too, he's got spoons that bend, thart just screams cool.

As for Pikachu, I dislike that thing, the only time i'd wanna have anything to do with it is if it's deep fried and lying on a plate sprinkled with salt and paprika.