All I can say is, whoever made him is really bad at cloning.

Or maybe really good... I mean, cloning consists of taking adult DNA (Mew's) and putting it into a viable egg. (In mammals that's an egg cell, which also needs to be implanted into a surrogate, but Pokemon are egg-layers.) Since we know Mew can't breed, it can't have eggs (that whole 'laid an egg' thing is clearly a misreading). So where did they get the egg?

The answer is obvious: Mewtwo is an inadvertent hybrid between Mew and another, yet-unidentified Pokemon. Comparison time!

Compared to Mew, Mewtwo has:

-A more pronounced tail/stomach.
-Longer and more round-ended fingers and toes.
-Shoulder armour.
-Squarer ears.
-More height and longer limbs.
-A more pronounced neck.
-A blockier head.

What Pokemon could be the source of those? Let's see, if we limit ourselves to Kanto... well, Clefable looks promising. It's got the ears, the tail, the fingers. But no neck. Let's keep looking... the Abra lineage would give the shoulder stuff, ears, height, neck... most of it, actually.

So there we have it. Mew's DNA was implanted into an Abra egg. Clearly, a ruthless scientist stole an Abra's egg (remember, no-one knew Pokemon laid eggs at this point), mucked about with it, and claimed it was Mew's; no-one picked up on the similarities to Kadabra/Alakazam because, well, Abra are annoying as heck to get hold of. They'd never seen one.

^_^

hS

Legendary Pokemon can breed.

They just suck at it.

Seriously, one produces mutant babies every time, another is apparently prone to Amazonogenesis. How badly wrong do you think the other pairings would go?

...

...

... ohallright.